--dialect <DIALECT>

SQL dialect.

By default the native SQL of an RDBMS is used when using gdal vector sql. If using sql as a step of gdal vector pipeline, this is only true if the step preceding sql is read, otherwise the OGRSQL dialect is used.

If a datasource does not support SQL natively, the default is to use the OGRSQL dialect, which can also be specified with any data source.

The SQL SQLite dialect dialect can be chosen with the SQLITE and INDIRECT_SQLITE dialect values, and this can be used with any data source. Overriding the default dialect may be beneficial because the capabilities of the SQL dialects vary.

Supported dialects can be checked with gdal --format. For example:

$ gdal --format "PostgreSQL"
[...]
Supported SQL dialects: NATIVE OGRSQL SQLITE
[...]

$ gdal --format "ESRI Shapefile"
[...]
Supported SQL dialects: OGRSQL SQLITE
[...]