---
title: "SQL reference"
sidebarTitle: "Overview"
description: "The SQL surface: dialect, where a query runs, and a page per construct."
icon: table-list
keywords: ["sql", "datafusion", "flight sql", "reference", "dialect"]
---

<Badge color="red">Enterprise</Badge> SQL runs on a deployment. A local database
has no engine to plan a statement, so `execute_query` raises there -- see
[SDKs and SQL](/basics/apis).

This is a reference rather than a guide: one page per construct, syntax first.
The guides elsewhere in these docs show the same operations from the SDKs.

## The dialect {#dialect}

LanceDB executes SQL with [Apache DataFusion](https://datafusion.apache.org),
currently **version 54**. The grammar, built-in functions and type system are
DataFusion's, so anything its reference documents for that version works here
unchanged and is not reproduced.

What these pages add is the part that is LanceDB's: how a query reaches the
engine, how Lance columns appear to it, and the statements a lakehouse needs
that DataFusion has no concept of.

## Where a query runs {#execution}

Queries execute on the server and results come back as Arrow record batches --
nothing is converted to pandas or Python objects unless you ask. `execute_query`
hands back a reader as soon as the first batch is ready rather than when the
query finishes, so a large result set does not have to fit in memory before you
start reading it. See [Query and job](/basics/jobs#queries).

Served over an [Arrow Flight SQL](https://arrow.apache.org/docs/format/FlightSql.html)
endpoint, so any Flight SQL client reaches it.

## Reference {#reference}

**Reading data**

| | |
| --- | --- |
| [Data types](/sql/data-types) | how Lance columns appear to SQL, and pseudo-columns |
| [SELECT](/sql/select) | projection, filtering, ordering, set operations, CTEs |
| [Subqueries](/sql/subqueries) | scalar, `IN`, `EXISTS`, correlated, derived tables |
| [Joins](/sql/join) | inner, outer, cross, and namespace-qualified paths |
| [Aggregation](/sql/aggregation) | `GROUP BY`, `HAVING`, the aggregate set |
| [Window functions](/sql/window) | `OVER`, framing, ranking and offset functions |
| [Sampling](/sql/sampling) | `TABLESAMPLE`, by rows or by fragments |

**Changing things**

| | |
| --- | --- |
| [DDL](/sql/ddl) | tables, views, indexes, functions, columns, WAL |
| [DML](/sql/dml) | `INSERT`, `UPDATE`, `DELETE`, `COPY` |
| [REFRESH](/sql/refresh) | filling computed columns and materialized views |

**Introspection**

| | |
| --- | --- |
| [SHOW](/sql/show) | jobs, functions, materialized views, errors |
| [EXPLAIN](/sql/explain) | plans, and measuring them |

**Expressions**

| | |
| --- | --- |
| [Operators](/sql/operators) | comparison, logical, arithmetic, literals, precedence |
| [Functions](/sql/functions) | where to find each kind, and table functions |
| [Scalar functions](/sql/scalar-functions) | the per-row catalogue, and what Lance accelerates |
| [Prepared statements](/sql/prepared-statements) | planning once, executing many times |

## What SQL cannot do {#cannot}

| | |
| --- | --- |
| Vector search | no SQL form -- a query-builder operation |
| Merge insert | no SQL form -- needs a source relation and a per-match policy |
| `information_schema` | not enabled, so `SHOW TABLES` and `SHOW COLUMNS` fail |
| `PREPARE` / `EXECUTE` | preparation is a [protocol feature](/sql/prepared-statements), not a statement |
| Run on a local database | no engine to plan the statement |

Full-text search **is** available, as the [`fts()`](/sql/functions#fts) table
function and the [`contains_tokens`](/sql/scalar-functions#contains-tokens) predicate.

See [Limits](/basics/limits#sql) for the bounds these pages enforce.