Target & Version

Target & Version

Target dialect

PRQL allows specifying a target dialect at the top of the query, which allows PRQL to compile to a database-specific SQL flavor.

Examples

PRQL

prql target:sql.postgres
from employees
sort age
take 10

SQL

SELECT
  *
FROM
  employees
ORDER BY
  age
LIMIT
  10

PRQL

prql target:sql.mssql
from employees
sort age
take 10

SQL

SELECT
  TOP (10) *
FROM
  employees
ORDER BY
  age

Dialects

Supported

Supported dialects support all PRQL language features where possible, are tested on every commit, and we’ll endeavor to fix bugs.

sql.clickhouse
sql.duckdb
sql.generic 1
sql.mysql
sql.postgres
sql.sqlite

Unsupported

Unsupported dialects have implementations in the compiler, but are tested minimally or not at all, and may have gaps for some features.

We’re open to contributions to improve our coverage of these, and to adding additional dialects.

sql.glaredb
sql.mssql
sql.ansi
sql.bigquery
sql.snowflake

Priority of targets

The compile target of a query is defined in the query’s header or as an argument to the compiler. option. The argument to the compiler takes precedence.

For example, the following shell example specifies sql.generic in the query and sql.duckdb in the --target option of the prqlc compile command. In this case, sql.duckdb takes precedence and the SQL output is based on the DuckDB dialect.

echo 'prql target:sql.generic
      from foo' | prqlc compile --target sql.duckdb

To use the target described in the query, a special target sql.any can be specified in the compiler option.

echo 'prql target:sql.generic
      from foo' | prqlc compile --target sql.any

Version

PRQL allows specifying a version of the language in the PRQL header, like:

PRQL

prql version:"0.10.0"
from employees

SQL

SELECT
  *
FROM
  employees

This has two roles, one of which is implemented:

The compiler will raise an error if the compiler is older than the query version. This prevents confusing errors when queries use newer features of the language but the compiler hasn’t yet been upgraded.
The compiler will compile for the major version of the query. This allows the language to evolve without breaking existing queries, or forcing multiple installations of the compiler. This isn’t yet implemented, but is a gating feature for PRQL 1.0.

The version of the compiler currently in use can be called using the special function std.prql_version in PRQL.

PRQL

[{version = prql_version}]

SQL

WITH table_0 AS (
  SELECT
    '0.10.0' AS version
)
SELECT
  version
FROM
  table_0

Note

This function std.prql_version may be replaced in the future by something like prql.version.

1: while there’s no “generic” DB to test sql.generic against, we still count it as supported.

12. Target & version