23.1.2. Database

23.1.2.1. Export to PostgreSQL

Exports a vector layer to a PostgreSQL database, creating a new relation. If a relation with the same name exists, it can be removed before the new relation is created. Prior to this a connection between QGIS and the PostgreSQL database has to be created (see eg Creating a stored Connection).

23.1.2.1.1. Parameters

Label	Name	Type	Description
Layer to import	INPUT	[vector: any]	Vector layer to add to the database
Database (connection name)	DATABASE	[string]	Name of the database connection (not the database name). Existing connections will be shown in the combobox.
Schema (schema name) Optional	SCHEMA	[string] Default: ‘public’	Name of the schema to store the data. It can be a new one or already exist.
Table to import to (leave blank to use layer name) Optional	TABLENAME	[string] Default: ‘’	Defines a table name for the imported vector file. If nothing is added, the layer name will be used.
Primary key field Optional	PRIMARY_KEY	[tablefield: any]	Sets the primary key field from an existing field in the vector layer. A column with unique values can be used as Primary key for the database.
Geometry column	GEOMETRY_COLUMN	[string] Default: ‘geom’	Defines the name of the geometry column in the new PostGIS table. Geometry information for the features is stored in this column.
Encoding Optional	ENCODING	[string] Default: ‘UTF-8’	Defines the encoding of the output layer
Overwrite	OVERWRITE	[boolean] Default: True	If the specified table exists, setting this option to True will make sure that it is deleted and a new table will be created before the features are added. If this option is False and the table exists, the algorithm will throw an exception (“relation already exists”).
Create spatial index	CREATEINDEX	[boolean] Default: True	Specifies whether to create a spatial index or not
Convert field names to lowercase	LOWERCASE_NAMES	[boolean] Default: True	Converts the field names of the input vector layer to lowercase
Drop length constraint on character fields	DROP_STRING_LENGTH	[boolean] Default: False	Should length constraints on character fields be dropped or not
Create single-part geometries instead of multi-part	FORCE_SINGLEPART	[boolean] Default: False	Should the features of the output layer be single-part instead of multi-part. By default the existing geometries information are preserved.

23.1.2.1.2. Outputs

The algorithm has no output.

23.1.2.1.3. Python code

Algorithm ID: qgis:importintopostgis

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.2.2. Export to SpatiaLite

Exports a vector layer to a SpatiaLite database. Prior to this a connection between QGIS and the SpatiaLite database has to be created (see eg SpatiaLite Layers).

23.1.2.2.1. Parameters

Label	Name	Type	Description
Layer to import	INPUT	[vector: any]	Vector layer to add to the database
File database	DATABASE	[vector: any]	The SQLite/SpatiaLite database file to connect to
Table to import to (leave blank to use layer name) Optional	TABLENAME	[string] Default: ‘’	Defines the table name for the imported vector file. If nothing is specified, the layer name will be used.
Primary key field Optional	PRIMARY_KEY	[tablefield: any]	Use a field in the input vector layer as the primary key
Geometry column	GEOMETRY_COLUMN	[string] Default: ‘geom’	Defines the name of the geometry column in the new SpatiaLite table. Geometry information for the features is stored in this column.
Encoding Optional	ENCODING	[string] Default: ‘UTF-8’	Defines the encoding of the output layer
Overwrite	OVERWRITE	[boolean] Default: True	If the specified table exists, setting this option to True will make sure that it is deleted and a new table will be created before the features of the layer is added. If this option is False and the table exists, the algorithm will throw an exception (“table already exists”).
Create spatial index	CREATEINDEX	[boolean] Default: True	Specifies whether to create a spatial index or not
Convert field names to lowercase	LOWERCASE_NAMES	[boolean] Default: True	Convert the field names of the input vector layer to lowercase
Drop length constraint on character fields	DROP_STRING_LENGTH	[boolean] Default: False	Should length constraints on character fields be dropped or not
Create single-part geometries instead of multi-part	FORCE_SINGLEPART	[boolean] Default: False	Should the features of the output layer be single-part instead of multi-part. By default the existing geometries information are preserved.

23.1.2.2.2. Outputs

The algorithm has no output.

23.1.2.2.3. Python code

Algorithm ID: qgis:importintospatialite

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.2.3. Package layers

Adds layers to a GeoPackage.

If the GeoPackage exists and Overwrite existing GeoPackage is checked, it will be overwritten (removed and recreated). If the GeoPackage exists and Overwrite existing GeoPackage is not checked, the layer will be appended.

23.1.2.3.1. Parameters

Label	Name	Type	Description
Input layers	LAYERS	[vector: any] [list]	The (vector) layers to import into the GeoPackage. Raster layers are not supported. If a raster layer is added, a QgsProcessingException will be thrown.
Overwrite existing GeoPackage	OVERWRITE	[boolean] Default: False	If the specified GeoPackage exists, setting this option to True will make sure that it is deleted and a new one will be created before the layers are added. If set to False, layers will be appended.
Save layer styles into GeoPackage	SAVE_STYLES	[boolean] Default: True	Save the layer styles
Destination GeoPackage	OUTPUT	[file]	If not specified the GeoPackage will be saved in the temporary folder.

23.1.2.3.2. Outputs

Label	Name	Type	Description
Layers within new package	OUTPUT_LAYERS	[string] [list]	The list of layers added to the GeoPackage.

23.1.2.3.3. Python code

Algorithm ID: qgis:package

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.2.4. PostgreSQL execute and load SQL

Allows a SQL database query to be performed on a PostgreSQL database connected to QGIS and loads the result. The algorithm won’t create a new layer: it is designed to run queries on the layer itself.

Example

1. Set all the values of an existing field to a fixed value. The SQL query string will be:

   UPDATE your_table SET field_to_update=20;
   

   In the example above, the values of the field field_to_update of the table your_table will be all set to 20.

2. Create a new area column and calculate the area of each feature with the ST_AREA PostGIS function.

   -- Create the new column "area" on the table your_table"
   ALTER TABLE your_table ADD COLUMN area double precision;
   -- Update the "area" column and calculate the area of each feature:
   UPDATE your_table SET area=ST_AREA(geom);
   

See also

PostgreSQL execute SQL, Execute SQL, SpatiaLite execute SQL

23.1.2.4.1. Parameters

Label	Name	Type	Description
Database (connection name)	DATABASE	[string]	The database connection (not the database name). Existing connections will be shown in the combobox.
SQL query	SQL	[string]	Defines the SQL query, for example 'UPDATE my_table SET field=10'.
Unique ID field name	ID_FIELD	[string] Default: id	Sets the primary key field (a column in the result table)
Geometry field name Optional	GEOMETRY_FIELD	[string] Default: ‘geom’	Name of the geometry column (a column in the result table)

23.1.2.4.2. Outputs

Label	Name	Type	Description
SQL layer	OUTPUT	[vector: any]	The resulting vector layer to be loaded into QGIS.

23.1.2.4.3. Python code

Algorithm ID: qgis:postgisexecuteandloadsql

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.2.5. PostgreSQL execute SQL

Allows a SQL database query to be performed on a PostgreSQL database connected to QGIS. The algorithm won’t create a new layer: it is designed to run queries on the layer itself.

Example

1. Set all the values of an existing field to a fixed value. The SQL query string will be:

   UPDATE your_table SET field_to_update=20;
   

   In the example above, the values of the field field_to_update of the table your_table will be all set to 20.

2. Create a new area column and calculate the area of each feature with the ST_AREA PostGIS function.

   -- Create the new column "area" on the table your_table"
   ALTER TABLE your_table ADD COLUMN area double precision;
   -- Update the "area" column and calculate the area of each feature:
   UPDATE your_table SET area=ST_AREA(geom);
   

See also

PostgreSQL execute and load SQL, Execute SQL, SpatiaLite execute SQL

23.1.2.5.1. Parameters

Label	Name	Type	Description
Database (connection name)	DATABASE	[string]	The database connection (not the database name). Existing connections will be shown in the combobox.
SQL query	SQL	[string]	Defines the SQL query, for example 'UPDATE my_table SET field=10'.

23.1.2.5.2. Outputs

No output is created. The SQL query is executed in place.

23.1.2.5.3. Python code

Algorithm ID: qgis:postgisexecutesql

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.2.6. SpatiaLite execute SQL

Allows a SQL database query to be performed on a SpatiaLite database connected to QGIS. The algorithm won’t create a new layer: it is designed to run queries on the layer itself.

See also

PostgreSQL execute SQL, Execute SQL

For some SQL query examples see PostGIS SQL Query Examples.

23.1.2.6.1. Parameters

Label	Name	Type	Description
File Database	DATABASE	[vector] Default: not set	The SQLite/SpatiaLite database file to connect to
SQL query	SQL	[string] Default: ‘’	Defines the SQL query, for example 'UPDATE my_table SET field=10'.

23.1.2.6.2. Outputs

No output is created. The SQL query is executed in place.

23.1.2.6.3. Python code

Algorithm ID: qgis:spatialiteexecutesql

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.