# Using - [Configuring Environments](https://docs.lenses.io/latest/user-guide/using/configuring-environments.md): Create a Lenses environment, start its agent, and connect Kafka services - [Discovering Topics & Schemas](https://docs.lenses.io/latest/user-guide/using/discovering-topics-and-schemas.md): Understand how to discover Kafka topics and schemas in Lenses - [Using SQL to query Kafka](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka.md): Understand the Lenses SQL Snapshot Engine to query data in Kafka - [Concepts](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/concepts.md): Understand Lenses SQL Snapshot concepts engine for Apache Kafka - [Best practices](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/best-practices.md): Understand best practices for Lenses SQL Snapshot engine for Apache Kafka - [Metadata fields](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/metadata-fields.md): Understand using Kafka topic metadata fields in Lenses SQL Snapshot concepts engine for Apache Kafka - [Filter by timestamp or offset](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/filter-by-timestamp-or-offset.md): Understand using Kafka topics by timestamp or offset in Lenses SQL Snapshot concepts engine for Apache Kafka - [Filtering](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/filtering.md): Understand using filters when querying Kafka topic data with Lenses SQL Snapshot concepts engine for Apache Kafka - [Limit & Sampling](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/limit-and-sampling.md): Understand using limits and sampling when querying Kafka topic data with Lenses SQL Snapshot concepts engine for Apache Kafka - [Managing queries](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/managing-queries.md): Understand to manage queries for Lenses SQL Snapshot concepts engine for Apache Kafka - [Creating & deleting Kafka topics](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/creating-and-deleting-kafka-topics.md): Understand how to create and delete Kafka topics with Lenses SQL Snapshot concepts engine for Apache Kafka - [Inserting & deleting data](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/inserting-and-deleting-data.md): Understand how to insert and delete Kafka topic data with Lenses SQL Snapshot concepts engine for Apache Kafka - [Joining topics](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/joining-topics.md): Understand how to join Kafka topic data when querying with Lenses SQL Snapshot concepts engine for Apache Kafka - [Arrays](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/arrays.md): Understand querying arrays in Kafka topic data with Lenses SQL Snapshot concepts engine for Apache Kafka - [Aggregations](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/aggregations.md): Understand aggregating Kafka topic data with Lenses SQL Snapshot concepts engine for Apache Kafka - [Views & synonyms](https://docs.lenses.io/latest/user-guide/using/using-sql-to-query-kafka/views-and-synonyms.md): Understand using views and synonyms with Lenses SQL Snapshot concepts engine for Apache Kafka - [Process data with SQL Processors](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors.md): Understand how to do streaming processing with Lenses SQL Processors on Apache Kafka - [Concepts](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/concepts.md): Understand the concepts of Lenses SQL Processors for Apache Kafka - [Time & Windows](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/time-and-windows.md): Understand the time and windowing of data in Kafka with Lenses SQL Processors. - [Projections](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/projections.md): Understand using projections for data in Kafka with Lenses SQL Processors. - [Joins](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/joins.md): Understand how to join data in Kafka with in Lenses SQL Processors. - [Lateral Joins](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/lateral-joins.md): Understand how to use lateral joins for data in Kafka with Lenses SQL Processors. - [Aggregations](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/aggregations.md): Understand how to aggregate data in Kafka with Lenses SQL Processors. - [Nullibility](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/nullibility.md): Understand handling nulls values in Kafka data with Lenses SQL Processors. - [Storage format](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/storage-format.md): Understand the storage formats of data in Kafka supported by Lenses SQL Processors. - [Settings](https://docs.lenses.io/latest/user-guide/using/process-data-with-sql-processors/settings.md): Understand using settings in Lenses SQL Processors to process data in Kafka. - [Share and replicate data](https://docs.lenses.io/latest/user-guide/using/share-and-replicate-data.md): Understand how to replicate data between Kafka clusters with Lenses - [Kafka Connections](https://docs.lenses.io/latest/user-guide/using/share-and-replicate-data/kafka-connections.md): Understand Kafka Connections and their usage in Lenses - [Kafka to Kafka Replicator](https://docs.lenses.io/latest/user-guide/using/share-and-replicate-data/kafka-to-kafka-replicator.md): Understand how to manage Kafka to Kafka data replication in Lenses. - [Authorization Guide](https://docs.lenses.io/latest/user-guide/using/share-and-replicate-data/kafka-to-kafka-replicator/authorization-guide.md) - [Application Migration](https://docs.lenses.io/latest/user-guide/using/share-and-replicate-data/application-migration.md): Understand how to migration applications (consumer groups) from one Kafka cluster to another - [Integrating data with Kafka Connect](https://docs.lenses.io/latest/user-guide/using/integrating-data-with-kafka-connect.md): Understand how to create and manage Kafka Connectors in Lenses - [Sources](https://docs.lenses.io/latest/user-guide/using/integrating-data-with-kafka-connect/sources.md): Understand the available Apache 2.0 Source Connectors from Lenses. Lenses can also work with any other Kafka Connect Connector. - [Sinks](https://docs.lenses.io/latest/user-guide/using/integrating-data-with-kafka-connect/sinks.md): Understand the available Apache 2.0 Sink Connectors from Lenses. Lenses can also work with any other Kafka Connect Connector. - [Secret Providers](https://docs.lenses.io/latest/user-guide/using/integrating-data-with-kafka-connect/secret-providers.md): Understand the available Apache 2.0 Connect Secret Providers from Lenses. - [Register your own Applications](https://docs.lenses.io/latest/user-guide/using/register-your-own-applications.md): Understand external applications in Lenses. - [Registering External Apps in Lenses](https://docs.lenses.io/latest/user-guide/using/register-your-own-applications/registering-external-apps-in-lenses.md): Understand how to register an external app in Lenses via the UI - [Registering External Apps via REST](https://docs.lenses.io/latest/user-guide/using/register-your-own-applications/registering-external-apps-via-rest.md): Understand how to register an external app in Lenses via a REST call - [Registering External Apps via SDK](https://docs.lenses.io/latest/user-guide/using/register-your-own-applications/registering-external-apps-via-sdk.md): Understand how to register an external app in Lenses via Java SDK - [MCP Server](https://docs.lenses.io/latest/user-guide/using/mcp-server.md): Understand the Lenses MCP Server. - [Security](https://docs.lenses.io/latest/user-guide/using/security.md): Understand Lenses security and IAM model - [Lenses Resource Names](https://docs.lenses.io/latest/user-guide/using/security/lenses-resource-names.md): Understand Lenses LRNs for use in Lenses IAM modal - [IAM Reference](https://docs.lenses.io/latest/user-guide/using/security/iam-reference.md): This page describes the IAM Reference options. - [OAuth 2.1](https://docs.lenses.io/latest/user-guide/using/security/oauth-2.1.md): Understand Lenses OAuth - [Example Policies](https://docs.lenses.io/latest/user-guide/using/security/example-policies.md): Example policies for Lenses IAM. - [Governance](https://docs.lenses.io/latest/user-guide/using/governance.md): Understand how to use the governance capabilities of Lenses - [Data policies](https://docs.lenses.io/latest/user-guide/using/governance/data-policies.md): Understand how to apply data policies for Kafka in Lenses - [Audits](https://docs.lenses.io/latest/user-guide/using/governance/audits.md): Understand how to view and manage auditing in Lenses - [Kafka ACLs](https://docs.lenses.io/latest/user-guide/using/governance/kafka-acls.md): Understand how to manage Kafka Quotas in Lenses - [Kafka Quotas](https://docs.lenses.io/latest/user-guide/using/governance/kafka-quotas.md): Understand how to manage Kafka Quotas in Lenses - [Alerting & Monitoring](https://docs.lenses.io/latest/user-guide/using/alerting-and-monitoring.md): Understand how to set up alerting and monitoring in Lenses. - [Alert Integration](https://docs.lenses.io/latest/user-guide/using/alerting-and-monitoring/alert-integration.md): Understand which alerting systems Lenses can send alerts to. - [Alert Rules](https://docs.lenses.io/latest/user-guide/using/alerting-and-monitoring/alert-rules.md): Understand how to set up consumer, producer and infrastructure alerting rules in Lenses. - [Alert Reference](https://docs.lenses.io/latest/user-guide/using/alerting-and-monitoring/alert-reference.md): This page describes the alert references for Lenses. - [Tutorials](https://docs.lenses.io/latest/user-guide/using/tutorials.md) - [SQL Processors](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors.md) - [Data formats](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/data-formats.md) - [Changing data formats](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/data-formats/changing-data-formats.md): Tutorial on how to change the format of data in a Kafka topic from JSON to AVRO with Lenses SQL Processors. - [Rekeying data](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/data-formats/rekeying-data.md): This page describes a tutorial to rekey data in a Kafka topic with Lenses SQL Processors. - [Controlling AVRO record names and namespaces](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/data-formats/controlling-avro-record-names-and-namespaces.md): This page a tutorial to control AVRO record names and namespaces with Lenses SQL Processors. - [Changing the shape of data](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/data-formats/changing-the-shape-of-data.md): This page describe a tutorial to change the shape (fields) of data in a Kafka topic using Lenses SQL Processors. - [Filtering & Joins](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/filtering-and-joins.md) - [Filtering data](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/filtering-and-joins/filtering-data.md): This page describes a tutorial to filter records in a Kafka topic with Lenses SQL Processors. - [Enriching data streams](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/filtering-and-joins/enriching-data-streams.md): This page describes a tutorial to enrich a Kafka topic using Lenses SQL Processors. - [Joining streams of data](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/filtering-and-joins/joining-streams-of-data.md): This page describes a tutorial joining Kafka topics with Lenses SQL Processors. - [Using multiple topics](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/filtering-and-joins/using-multiple-topics.md): This page describes a tutorial to use multiple Kafka topics in a Lenses SQL Processor. - [Aggregations](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/aggregations.md) - [Aggregating data in a table](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/aggregations/aggregating-data-in-a-table.md): This page describes a tutorial to aggregate Kafka topic data into a table using Lenses SQL Processors. - [Aggregating streams](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/aggregations/aggregating-streams.md): This page describes a tutorial to aggregate data Kafka topic data into a stream using Lenses SQL Processors - [Time window aggregations](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/aggregations/time-window-aggregations.md): This page describes a tutorial to perform time windowed aggregations on Kafka topic data with Lenses SQL Processors. - [Complex types](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/complex-types.md) - [Unwrapping complex types](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/complex-types/unwrapping-complex-types.md): This page describes a tutorial to unwrap a complex data type in a Kafka topic using Lenses SQL Processors. - [Working with Arrays](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/complex-types/working-with-arrays.md): This page describes a tutorial on how to work with array data in your Kafka topics using Lenses SQL Processors. - [Controlling event time](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-processors/controlling-event-time.md): This describes how to control event time for data in your Kafka topics with Lenses SQL Processors. - [SQL Studio](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-studio.md) - [Querying data](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-studio/querying-data.md): This page describes a tutorial for querying data with SQL Studio. - [Accessing headers](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-studio/accessing-headers.md): This page describes a tutorial for access headers via SQL Studio. - [Deleting data from compacted topics](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-studio/deleting-data-from-compacted-topics.md): This page describes a tutorial for deleting data in compacted topics from SQL Studio. - [Working with JSON](https://docs.lenses.io/latest/user-guide/using/tutorials/sql-studio/working-with-json.md): This page describes a tutorial on how to work with JSON in Lenses SQL. - [SQL Reference](https://docs.lenses.io/latest/user-guide/using/sql-reference.md): This page describes the SQL Reference for Lenses SQL Processors for data in Kafka. - [Expressions](https://docs.lenses.io/latest/user-guide/using/sql-reference/expressions.md): This page describes the expressions in Lenses SQL Processors. - [Functions](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions.md): This page describes how to use functions in Lenses SQL Processors. - [Aggregate](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate.md): This section describes how to use AGGREGATE functions in Lenses SQL. - [AVG](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/avg.md): This page describes the AVG function in Lenses SQL. - [BOTTOMK](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/bottomk.md): This page describes the BOTTOMK function in Lenses SQL. - [COLLECT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/collect.md): This page describe the COLLECT function in Lenses SQL. - [COLLECT\_UNIQUE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/collect_unique.md): This page describes the COLLECT\_UNIQUE function in Lenses SQL. - [COUNT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/count.md): This page describes the COUNT function in Lenses SQL. - [FIRST](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/first.md): This page describes the FIRST function in Lenses SQL. - [LAST](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/last.md): This page describes the LAST function in Lenses SQL. - [MAXK](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/maxk.md): This page describes the MAXK function in Lenses SQL. - [MAXK\_UNIQUE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/maxk_unique.md): This page describes the MAXK\_UNIQUE function in Lenses SQL. - [MINK](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/mink.md): This page describes the MINK function in Lenses SQL. - [MINK\_UNIQUE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/mink_unique.md): This page describes the MINK\_UNIQUE function in Lenses SQL. - [SUM](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/sum.md): This page describes the SUM function in Lenses SQL. - [TOPK](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/aggregate/topk.md): This page describes the TOPK function in Lenses SQL. - [Array](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array.md): This page describes how to use ARRAY functions in Lenses SQL Processors. - [ELEMENT\_OF](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/element_of.md): This page describes the ELEMENT\_OF function in Lenses SQL. - [FLATTEN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/flatten.md): This page describes the FLATTEN function in Lenses SQL. - [IN\_ARRAY](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/in_array.md): This page describes the IN\_ARRAY function in Lenses SQL. - [REPEAT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/repeat.md): This page describes the REPEAT function in Lenses SQL. - [SIZEOF](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/sizeof.md): This page describes the SIZEOF function in Lenses SQL. - [ZIP\_ALL](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/zip_all.md): This page describes the ZIP\_ALL function in Lenses SQL. - [ZIP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/array/zip.md): This page describes the ZIP function in Lenses SQL. - [Conditions](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/conditions.md): This page describes how to use Conditions in Lenses SQL Processors. - [Conversion](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/conversion.md): This page describes how to use conversion or CAST functions in Lenses SQL Processors. - [Date & Time](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time.md): This page describes how to use date and time functions in Lenses SQL Processors. - [CONVERT\_DATETIME](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/convert_datetime.md): This page describes the CONVERT\_DATETIME function in Lenses SQL. - [DATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/date.md): This page describes the DATE function in Lenses SQL. - [DATETIME](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/datetime.md): This page describes the DATETIME function in Lenses SQL. - [EXTRACT\_TIME](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/extract_time.md): This page describes the EXTRACT\_TIME function in Lenses SQL. - [EXTRACT\_DATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/extract_date.md): This page describes the EXTRACT\_DATE function in Lenses SQL. - [FORMAT\_DATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/format_date.md): This page describes the FORMAT\_DATE function in Lenses SQL. - [FORMAT\_TIME](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/format_time.md): This page describes the FORMAT\_TIME function in Lenses SQL. - [FORMAT\_TIMESTAMP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/format_timestamp.md): This page describes the FORMAT\_TIMESTAMP function in Lenses SQL. - [HOUR](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/hour.md): This page describes the HOUR function in Lenses SQL. - [MONTH\_TEXT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/month_text.md): This page describes the MONTH\_TEXT function in Lenses SQL. - [MINUTE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/minute.md): This page describes the MINUTE function in Lenses SQL. - [MONTH](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/month.md): This page describes the MONTH function in Lenses SQL. - [PARSE\_DATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/parse_date.md): This page describes the PARSE\_DATE function in Lenses SQL. - [PARSE\_TIME\_MILLIS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/parse_time_millis.md): This page describes the PARSE\_TIME\_MILLIS function in Lenses SQL. - [PARSE\_TIME\_MICROS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/parse_time_micros.md): This page describes the PARSE\_TIME\_MICROS function in Lenses SQL. - [PARSE\_TIMESTAMP\_MILLIS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/parse_timestamp_millis.md): This page describes the PARSE\_TIMESTAMP\_MILLIS function in Lenses SQL. - [PARSE\_TIMESTAMP\_MICROS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/parse_timestamp_micros.md): This page describes the PARSE\_TIMESTAMP\_MICROS function in Lenses SQL. - [SECOND](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/second.md): This page describes the SECOND function in Lenses SQL. - [TIMESTAMP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/timestamp.md): This page describes the TIMESTAMP function in Lenses SQL. - [TIME\_MICROS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/time_micros.md): This page describes the TIME\_MICROS function in Lenses SQL. - [TIMESTAMP\_MICROS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/timestamp_micros.md): This page describes the TIMESTAMP\_MICROS function in Lenses SQL. - [TIME\_MILLIS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/time_millis.md): This page describes the TIME\_MILLIS function in Lenses SQL. - [TIMESTAMP\_MILLIS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/timestamp_millis.md): This page describes the TIMESTAMP\_MILLIS function in Lenses SQL. - [TO\_DATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/to_date.md): This page describes the TO\_DATE function in Lenses SQL. - [TO\_DATETIME](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/to_datetime.md): This page describes the TO\_DATETIME function in Lenses SQL. - [TOMORROW](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/tomorrow.md): This page describes the TOMORROW function in Lenses SQL. - [TO\_TIMESTAMP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/to_timestamp.md): This page describes the TO\_TIMESTAMP function in Lenses SQL. - [YEAR](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/year.md): This page describes the YEAR function in Lenses SQL. - [YESTERDAY](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/date-and-time/yesterday.md): This page describes the YESTERDAY function in Lenses SQL. - [Headers](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers.md): This page describes how to use HEADER functions in Lenses SQL Processors. - [HEADERASSTRING](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers/headerasstring.md): This page describes the HEADERASSTRING function in Lenses SQL. - [HEADERASINT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers/headerasint.md): This page describes the HEADERASINT function in Lenses SQL. - [HEADERASLONG](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers/headeraslong.md): This page describes the HEADERASLONG function in Lenses SQL. - [HEADERASDOUBLE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers/headerasdouble.md): This page describes the HEADERASDOUBLE function in Lenses SQL. - [HEADERASFLOAT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers/headerasfloat.md): This page describes the HEADERASFLOAT function in Lenses SQL. - [HEADERKEYS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/headers/headerkeys.md): This page describes the HEADERKEYS function in Lenses SQL. - [JSON](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/json.md): This page describes the JSON functions in Lenses SQL. - [JSON\_EXTRACT\_FIRST](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/json/json_extract_first.md): This page describes the JSON\_EXTRACT\_FIRST function in Lenses SQL. - [JSON\_EXTRACT\_ALL](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/json/json_extract_all.md): This page describes the JSON\_EXTRACT\_ALL function in Lenses SQL. - [Numeric](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric.md): This page describes how to use numeric functions in Lenses SQL Processors. - [ABS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/abs.md): This page describes the ABS function in Lenses SQL. - [ACOS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/acos.md): This page describes the ACOS function in Lenses SQL. - [ASIN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/asin.md): This page describes the ASIN function in Lenses SQL. - [ATAN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/atan.md): This page describes the ATAN function in Lenses SQL. - [CBRT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/cbrt.md): This page describes the CBRT function in Lenses SQL. - [CEIL](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/ceil.md): This page describes the CEIL function in Lenses SQL. - [COSH](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/cosh.md): This page describes the COSH function in Lenses SQL. - [COS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/cos.md): This page describes the COS function in Lenses SQL. - [DEGREES](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/degrees.md): This page describes the DEGRESS function in Lenses SQL. - [DISTANCE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/distance.md): This page describes the DISTANCE function in Lenses SQL. - [FLOOR](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/floor.md): This page describes the FLOOR function in Lenses SQL. - [MAX](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/max.md): This page describes the MAX function in Lenses SQL. - [MIN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/min.md): This page describes the MIN function in Lenses SQL. - [MOD](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/mod.md): This page describes the MOD function in Lenses SQL. - [NEG](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/neg.md): This page describes the NEG function in Lenses SQL. - [POW](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/pow.md): This page describes the POW function in Lenses SQL. - [RADIANS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/radians.md): This page describes the RADIANS function in Lenses SQL. - [RANDINT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/randint.md): This page describes the RANDINT function in Lenses SQL. - [ROUND](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/round.md): This page describes the ROUND function in Lenses SQL. - [SIGN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/sign.md): This page describes the SIGN function in Lenses SQL. - [SINH](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/sinh.md): This page describes the SINH function in Lenses SQL. - [SIN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/sin.md): This page describes the SIN function in Lenses SQL. - [SQRT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/sqrt.md): This page describes the SQRT function in Lenses SQL. - [TANH](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/tanh.md): This page describes the TANH function in Lenses SQL. - [TAN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/numeric/tan.md): This page describes the TAN function in Lenses SQL. - [Nulls](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/nulls.md): This page describes how to use NULL functions in Lenses SQL Processors. - [ISNULL](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/nulls/isnull.md): This page describes the ISNULL function in Lenses SQL. - [ISNOTNULL](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/nulls/isnotnull.md): This page describes the ISNOTNULL function in Lenses SQL. - [COALESCE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/nulls/coalesce.md): This page describes the COALESCE function in Lenses SQL. - [AS\_NULLABLE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/nulls/as_nullable.md): This page describes the AS\_NULLABLE function in Lenses SQL. - [AS\_NON\_NULLABLE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/nulls/as_non_nullable.md): This page describes the AS\_NON\_NULLABLE function in Lenses SQL. - [Obfuscation](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation.md): This page describes how to use obfuscation functions in Lenses SQL Processors. - [ANONYMIZE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/anonymize.md): This page describes the ANONYMIZE function in Lenses SQL. - [MASK](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/mask.md): This page describes the MASK function in Lenses SQL. - [EMAIL](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/email.md): This page describes the EMAIL function in Lenses SQL. - [FIRST1](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/first1.md): This page describe the FIRST1 function in Lenses SQL. - [FIRST2](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/first2.md): This page describes the FIRST2 function in Lenses SQL. - [FIRST3](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/first3.md): This page describes the FIRST3 function in Lenses SQL. - [FIRST4](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/first4.md): This page describes the FIRST4 function in Lenses SQL. - [LAST1](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/last1.md): This page describes the LAST1 function in Lenses SQL. - [LAST2](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/last2.md): This page describes the LAST2 function in Lenses SQL. - [LAST3](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/last3.md): This page describes the LAST3 function in Lenses SQL. - [LAST4](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/last4.md): This page describes the LAST4 function in Lenses SQL. - [INITIALS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/obfuscation/initials.md): This page describes the INITALS function in Lenses SQL. - [Offsets](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/offsets.md): This page describes how to use offset functions in Lenses SQL Processors. - [Schema](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/schema.md): This page describes how to use schema functions in Lenses SQL Processors. - [TYPEOF](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/schema/typeof.md): This page describes the TYPEOF function in Lenses SQL. - [DUMP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/schema/dump.md): This page describes the DUMP function in Lenses SQL. - [String](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string.md): This page describes how to use string functions in Lenses SQL Processors. - [ABBREVIATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/abbreviate.md): This page describes the ABBREVIATE function in Lenses SQL. - [BASE64](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/base64.md): This page describes the BASE64function in Lenses SQL. - [CAPITALIZE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/capitalize.md): This page describes the CAPITALIZE function in Lenses SQL. - [CENTER](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/center.md): This page describes the CENTER function in Lenses SQL. - [CHOP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/chop.md): This page describes the CHOP function in Lenses SQL. - [CONCAT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/concat.md): This page describes the CONCAT function in Lenses SQL. - [CONTAINS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/contains.md): This page describes the CONTAINS function in Lenses SQL. - [DECODE64](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/decode64.md): This page describes the DECODE64 function in Lenses SQL. - [DELETEWHITESPACE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/deletewhitespace.md): This page describes the DELETEWHITESPACE function in Lenses SQL. - [DIGITS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/digits.md): This page describes the DIGITS function in Lenses SQL. - [DROPLEFT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/dropleft.md): This page describes the DROPLEFT function in Lenses SQL. - [DROPRIGHT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/dropright.md): This page describes the DROPRIGHT function in Lenses SQL. - [ENDSWITH](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/endswith.md): This page describes the ENDSWITH function in Lenses SQL. - [INDEXOF](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/indexof.md): This page describes the INDEXOF function in Lenses SQL. - [LEN](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/len.md): This page describes the LEN function in Lenses SQL. - [LOWER](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/lower.md): This page describes the LOWER function in Lenses SQL. - [LPAD](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/lpad.md): This page describes the LPAD function in Lenses SQL. - [MKSTRING](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/mkstring.md): This page describes the MKSTRING function in Lenses SQL. - [REGEXP](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/regexp.md): This page describes the REGEXP function in Lenses SQL. - [REGEX\_MATCHES](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/regex_matches.md): This page describes the REGEX\_MATCHES function in Lenses SQL. - [REPLACE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/replace.md): This page describes the REPLACE function in Lenses SQL. - [REVERSE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/reverse.md): This page describes the REVERSE function in Lenses SQL. - [RPAD](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/rpad.md): This page describes the REGEX\_MATCHES function in Lenses SQL. - [STARTSWITH](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/startswith.md): This page describes the STARTSWITH function in Lenses SQL. - [STRIPACCENTS](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/stripaccents.md): This page describes the STRIPACCENTS function in Lenses SQL. - [SUBSTR](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/substr.md): This page describes the SUBSTR function in Lenses SQL. - [SWAPCASE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/swapcase.md): This page describes the SWAPCASE function in Lenses SQL. - [TAKELEFT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/takeleft.md): This page describes the TAKELEFT function in Lenses SQL. - [TAKERIGHT](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/takeright.md): This page describes the TAKERIGHT function in Lenses SQL. - [TRIM](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/trim.md): This page describes the TRIM function in Lenses SQL. - [TRUNCATE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/truncate.md): This page describes the TRUNCATE function in Lenses SQL. - [UNCAPITALIZE](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/uncapitalize.md): This page describes the UNCAPITALIZE function in Lenses SQL. - [UPPER](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/upper.md): This page describes the UPPER function in Lenses SQL. - [UUID](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/string/uuid.md): This page describes the UUID function in Lenses SQL. - [User Defined Functions](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/user-defined-functions.md): This page describes how to write UDFs for Lenses SQL. - [User Defined Aggregate Functions](https://docs.lenses.io/latest/user-guide/using/sql-reference/functions/user-defined-aggregate-functions.md): This page describes how to use User defined functions in Lenses SQL Processors. - [Deserializers](https://docs.lenses.io/latest/user-guide/using/sql-reference/deserializers.md): This page describes how to use deserializers in Lenses. - [Supported data formats](https://docs.lenses.io/latest/user-guide/using/sql-reference/supported-data-formats.md): This page describes the support data formats for the Lenses SQL engines. - [Protobuf](https://docs.lenses.io/latest/user-guide/using/sql-reference/supported-data-formats/protobuf.md): This page describes how to use Profobuf with Lenses. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.lenses.io/latest/user-guide/using.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.