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diff --git a/doc/src/sgml/man7/DELETE.7 b/doc/src/sgml/man7/DELETE.7 new file mode 100644 index 0000000..4407306 --- /dev/null +++ b/doc/src/sgml/man7/DELETE.7 @@ -0,0 +1,320 @@ +'\" t +.\" Title: DELETE +.\" Author: The PostgreSQL Global Development Group +.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/> +.\" Date: 2021 +.\" Manual: PostgreSQL 13.4 Documentation +.\" Source: PostgreSQL 13.4 +.\" Language: English +.\" +.TH "DELETE" "7" "2021" "PostgreSQL 13.4" "PostgreSQL 13.4 Documentation" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +DELETE \- delete rows of a table +.SH "SYNOPSIS" +.sp +.nf +[ WITH [ RECURSIVE ] \fIwith_query\fR [, \&.\&.\&.] ] +DELETE FROM [ ONLY ] \fItable_name\fR [ * ] [ [ AS ] \fIalias\fR ] + [ USING \fIfrom_item\fR [, \&.\&.\&.] ] + [ WHERE \fIcondition\fR | WHERE CURRENT OF \fIcursor_name\fR ] + [ RETURNING * | \fIoutput_expression\fR [ [ AS ] \fIoutput_name\fR ] [, \&.\&.\&.] ] +.fi +.SH "DESCRIPTION" +.PP +\fBDELETE\fR +deletes rows that satisfy the +WHERE +clause from the specified table\&. If the +WHERE +clause is absent, the effect is to delete all rows in the table\&. The result is a valid, but empty table\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBTip\fR +.ps -1 +.br +.PP +\fBTRUNCATE\fR(7) +provides a faster mechanism to remove all rows from a table\&. +.sp .5v +.RE +.PP +There are two ways to delete rows in a table using information contained in other tables in the database: using sub\-selects, or specifying additional tables in the +USING +clause\&. Which technique is more appropriate depends on the specific circumstances\&. +.PP +The optional +RETURNING +clause causes +\fBDELETE\fR +to compute and return value(s) based on each row actually deleted\&. Any expression using the table\*(Aqs columns, and/or columns of other tables mentioned in +USING, can be computed\&. The syntax of the +RETURNING +list is identical to that of the output list of +\fBSELECT\fR\&. +.PP +You must have the +DELETE +privilege on the table to delete from it, as well as the +SELECT +privilege for any table in the +USING +clause or whose values are read in the +\fIcondition\fR\&. +.SH "PARAMETERS" +.PP +\fIwith_query\fR +.RS 4 +The +WITH +clause allows you to specify one or more subqueries that can be referenced by name in the +\fBDELETE\fR +query\&. See +Section\ \&7.8 +and +\fBSELECT\fR(7) +for details\&. +.RE +.PP +\fItable_name\fR +.RS 4 +The name (optionally schema\-qualified) of the table to delete rows from\&. If +ONLY +is specified before the table name, matching rows are deleted from the named table only\&. If +ONLY +is not specified, matching rows are also deleted from any tables inheriting from the named table\&. Optionally, +* +can be specified after the table name to explicitly indicate that descendant tables are included\&. +.RE +.PP +\fIalias\fR +.RS 4 +A substitute name for the target table\&. When an alias is provided, it completely hides the actual name of the table\&. For example, given +DELETE FROM foo AS f, the remainder of the +\fBDELETE\fR +statement must refer to this table as +f +not +foo\&. +.RE +.PP +\fIfrom_item\fR +.RS 4 +A table expression allowing columns from other tables to appear in the +WHERE +condition\&. This uses the same syntax as the +FROM +clause of a +\fBSELECT\fR +statement; for example, an alias for the table name can be specified\&. Do not repeat the target table as a +\fIfrom_item\fR +unless you wish to set up a self\-join (in which case it must appear with an alias in the +\fIfrom_item\fR)\&. +.RE +.PP +\fIcondition\fR +.RS 4 +An expression that returns a value of type +boolean\&. Only rows for which this expression returns +true +will be deleted\&. +.RE +.PP +\fIcursor_name\fR +.RS 4 +The name of the cursor to use in a +WHERE CURRENT OF +condition\&. The row to be deleted is the one most recently fetched from this cursor\&. The cursor must be a non\-grouping query on the +\fBDELETE\fR\*(Aqs target table\&. Note that +WHERE CURRENT OF +cannot be specified together with a Boolean condition\&. See +\fBDECLARE\fR(7) +for more information about using cursors with +WHERE CURRENT OF\&. +.RE +.PP +\fIoutput_expression\fR +.RS 4 +An expression to be computed and returned by the +\fBDELETE\fR +command after each row is deleted\&. The expression can use any column names of the table named by +\fItable_name\fR +or table(s) listed in +USING\&. Write +* +to return all columns\&. +.RE +.PP +\fIoutput_name\fR +.RS 4 +A name to use for a returned column\&. +.RE +.SH "OUTPUTS" +.PP +On successful completion, a +\fBDELETE\fR +command returns a command tag of the form +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE \fIcount\fR +.fi +.if n \{\ +.RE +.\} +.sp +The +\fIcount\fR +is the number of rows deleted\&. Note that the number may be less than the number of rows that matched the +\fIcondition\fR +when deletes were suppressed by a +BEFORE DELETE +trigger\&. If +\fIcount\fR +is 0, no rows were deleted by the query (this is not considered an error)\&. +.PP +If the +\fBDELETE\fR +command contains a +RETURNING +clause, the result will be similar to that of a +\fBSELECT\fR +statement containing the columns and values defined in the +RETURNING +list, computed over the row(s) deleted by the command\&. +.SH "NOTES" +.PP +PostgreSQL +lets you reference columns of other tables in the +WHERE +condition by specifying the other tables in the +USING +clause\&. For example, to delete all films produced by a given producer, one can do: +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE FROM films USING producers + WHERE producer_id = producers\&.id AND producers\&.name = \*(Aqfoo\*(Aq; +.fi +.if n \{\ +.RE +.\} +.sp +What is essentially happening here is a join between +films +and +producers, with all successfully joined +films +rows being marked for deletion\&. This syntax is not standard\&. A more standard way to do it is: +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE FROM films + WHERE producer_id IN (SELECT id FROM producers WHERE name = \*(Aqfoo\*(Aq); +.fi +.if n \{\ +.RE +.\} +.sp +In some cases the join style is easier to write or faster to execute than the sub\-select style\&. +.SH "EXAMPLES" +.PP +Delete all films but musicals: +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE FROM films WHERE kind <> \*(AqMusical\*(Aq; +.fi +.if n \{\ +.RE +.\} +.PP +Clear the table +films: +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE FROM films; +.fi +.if n \{\ +.RE +.\} +.PP +Delete completed tasks, returning full details of the deleted rows: +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE FROM tasks WHERE status = \*(AqDONE\*(Aq RETURNING *; +.fi +.if n \{\ +.RE +.\} +.PP +Delete the row of +tasks +on which the cursor +c_tasks +is currently positioned: +.sp +.if n \{\ +.RS 4 +.\} +.nf +DELETE FROM tasks WHERE CURRENT OF c_tasks; +.fi +.if n \{\ +.RE +.\} +.SH "COMPATIBILITY" +.PP +This command conforms to the +SQL +standard, except that the +USING +and +RETURNING +clauses are +PostgreSQL +extensions, as is the ability to use +WITH +with +\fBDELETE\fR\&. +.SH "SEE ALSO" +\fBTRUNCATE\fR(7) |