27.1.2. 数据库

27.1.2.1. 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 创建存储的连接).

参数

标注	名称	类型	描述
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) 可选	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) 可选	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 可选	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 可选	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.

输出

The algorithm has no output.

Python代码

Algorithm ID: qgis:importintopostgis

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。

27.1.2.2. 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图层).

参数

标注	名称	类型	描述
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) 可选	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 可选	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 可选	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.

输出

The algorithm has no output.

Python代码

Algorithm ID: qgis:importintospatialite

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。

27.1.2.3. 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.

参数

标注	名称	类型	描述
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
Save only selected features	SELECTED_FEATURES_ONLY	[boolean] Default: False	If a layer has a selection, setting this option to True will result in only selected features being saved. For layers without a selection all features will be saved.
Export related layers following relations defined in the project NEW in 3.28	EXPORT_RELATED_LAYERS	[boolean] Default: False	If an input layer has relations set in the project, setting this option to True will result in exporting also its related layer(s). If the layer has features selected, then only their related features will be exported unless the related layer was also an input layer.
Destination GeoPackage	OUTPUT	[file] Default: [Save to temporary file]	Specify where to store the GeoPackage file. One of Save to a Temporary File Save to File…

输出

标注	名称	类型	描述
Layers within new package	OUTPUT_LAYERS	[string] [list]	The list of layers added to the GeoPackage.

Python代码

Algorithm ID: native:package

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。

27.1.2.4. 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);
   

参见

PostgreSQL execute SQL, Execute SQL, SpatiaLite execute SQL

参数

标注	名称	类型	描述
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 可选	GEOMETRY_FIELD	[string] Default: 'geom'	Name of the geometry column (a column in the result table)

输出

标注	名称	类型	描述
SQL layer	OUTPUT	[vector: any]	The resulting vector layer to be loaded into QGIS.

Python代码

Algorithm ID: qgis:postgisexecuteandloadsql

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。

27.1.2.5. 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);
   

参见

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

参数

标注	名称	类型	描述
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'.

输出

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

Python代码

Algorithm ID: native:postgisexecutesql

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。

27.1.2.6. SpatiaLite execute SQL

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

参见

PostgreSQL execute SQL, Execute SQL

For some SQL query examples see PostGIS SQL Query Examples.

参数

标注	名称	类型	描述
File Database	DATABASE	[vector]	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'.

输出

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

Python代码

Algorithm ID: native:spatialiteexecutesql

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。

27.1.2.7. SpatiaLite execute SQL (registered DB)

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.

参见

PostgreSQL execute SQL, Execute SQL

For some SQL query examples see PostGIS SQL Query Examples.

参数

标注	名称	类型	描述
Database	DATABASE	[enumeration] Default: not set	Select a SQLite/SpatiaLite database connected to the current session
SQL query	SQL	[string] Default: ''	Defines the SQL query, for example 'UPDATE my_table SET field=10'.

输出

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

Python代码

Algorithm ID: native:spatialiteexecutesqlregistered

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

当你在数据处理工具箱某个算法前悬停时，算法 id 将会展现。*参数字*将会提供参数的名称与数值。参考详见`数据处理_控制台`以获取如何从Python控制台中运行数据处理算法。