---
name: v.db.droprow
description: "Removes a vector feature from a vector map through attribute selection."
keywords: [ vector, attribute table, database ]
---

# v.db.droprow

Removes a vector feature from a vector map through attribute selection.

=== "Command line"

    **v.db.droprow**
    **input**=*name*
    [**layer**=*string*]
    **where**=*sql_query*
    **output**=*name*
    [**--overwrite**]
    [**--verbose**]
    [**--quiet**]
    [**--qq**]
    [**--ui**]

    Example:

    ```sh
    v.db.droprow input=name where=sql_query output=name
    ```

=== "Python (grass.tools)"

    *grass.tools.Tools.v_db_droprow*(**input**,
        **layer**=*"1"*,
        **where**,
        **output**,
        **overwrite**=*None*,
        **verbose**=*None*,
        **quiet**=*None*,
        **superquiet**=*None*)

    Example:

    ```python
    tools = Tools()
    tools.v_db_droprow(input="name", where="sql_query", output="name")
    ```

    This grass.tools API is experimental in version 8.5 and expected to be stable in version 8.6.

=== "Python (grass.script)"

    *grass.script.run_command*("***v.db.droprow***",
        **input**,
        **layer**=*"1"*,
        **where**,
        **output**,
        **overwrite**=*None*,
        **verbose**=*None*,
        **quiet**=*None*,
        **superquiet**=*None*)

    Example:

    ```python
    gs.run_command("v.db.droprow", input="name", where="sql_query", output="name")
    ```

## Parameters

=== "Command line"

    **input**=*name* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    **layer**=*string*  
    &nbsp;&nbsp;&nbsp;&nbsp;Layer number or name  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *1*  
    **where**=*sql_query* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;WHERE conditions of SQL statement without 'where' keyword  
    &nbsp;&nbsp;&nbsp;&nbsp;Example: income &lt; 1000 and population &gt;= 10000  
    **output**=*name* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    **--overwrite**  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    **--help**  
    &nbsp;&nbsp;&nbsp;&nbsp;Print usage summary  
    **--verbose**  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    **--quiet**  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    **--qq**  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    **--ui**  
    &nbsp;&nbsp;&nbsp;&nbsp;Force launching GUI dialog

=== "Python (grass.tools)"

    **input** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **layer** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Layer number or name  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *1*  
    **where** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;WHERE conditions of SQL statement without 'where' keyword  
    &nbsp;&nbsp;&nbsp;&nbsp;Example: income &lt; 1000 and population &gt;= 10000  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, sql_query, *sql_query*  
    **output** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: output, vector, *name*  
    **overwrite** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **verbose** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **quiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **superquiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  

    Returns:

    **result** : grass.tools.support.ToolResult | None  
    If the tool produces text as standard output, a *ToolResult* object will be returned. Otherwise, `None` will be returned.

    Raises:

    *grass.tools.ToolError*: When the tool ended with an error.

=== "Python (grass.script)"

    **input** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **layer** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Layer number or name  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *1*  
    **where** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;WHERE conditions of SQL statement without 'where' keyword  
    &nbsp;&nbsp;&nbsp;&nbsp;Example: income &lt; 1000 and population &gt;= 10000  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, sql_query, *sql_query*  
    **output** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: output, vector, *name*  
    **overwrite** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **verbose** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **quiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **superquiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*

## DESCRIPTION

*v.db.droprow* removes vector object(s) (point, line, area, face etc.)
from a vector map through attribute selection in the table connected to
the given vector map. It automatically checks the connection for the
specified layer.

## NOTES

v.db.droprow is a front-end to *v.extract* (reverse selection) to allow
easier usage. The existing database connection(s) can be verified with
*v.db.connect*.

## EXAMPLES

Dropping all vector points without elevation attribute (North Carolina
data set):  

```sh
g.region raster=elevation -p
v.random output=rand5k_elev n=5000

v.db.addtable map=rand5k_elev column="elevation double precision"
v.what.rast vect=rand5k_elev rast=elevation column=elevation

# verify absence of some elevation attributes ("number of NULL attributes"):
v.univar rand5k_elev type=point column=elevation

# Remove all vector points lacking elevation attribute
v.db.droprow rand5k_elev output=rand5k_elev_filt where="elevation IS NULL"

# verify:
v.univar rand5k_elev_filt type=point column=elevation
```

## SEE ALSO

*[db.droptable](db.droptable.md), [db.execute](db.execute.md),
[v.db.addcolumn](v.db.addcolumn.md), [v.db.addtable](v.db.addtable.md),
[v.db.connect](v.db.connect.md), [v.db.dropcolumn](v.db.dropcolumn.md),
[v.db.droptable](v.db.droptable.md), [v.db.select](v.db.select.md),
[v.db.update](v.db.update.md)*

*[GRASS SQL interface](sql.md)*

## AUTHOR

Markus Neteler

## SOURCE CODE

Available at: [v.db.droprow source code](https://github.com/OSGeo/grass/tree/main/scripts/v.db.droprow)
([history](https://github.com/OSGeo/grass/commits/main/scripts/v.db.droprow))  
Latest change: Friday Feb 07 19:16:09 2025 in commit [a82a39f](https://github.com/OSGeo/grass/commit/a82a39f673b97fafcfce1604dc3e6015cb96487a)
