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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>dblink_build_sql_update</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="contrib-dblink-build-sql-delete.html" title="dblink_build_sql_delete" /><link rel="next" href="dict-int.html" title="F.11. dict_int" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">dblink_build_sql_update</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="contrib-dblink-build-sql-delete.html" title="dblink_build_sql_delete">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="dblink.html" title="F.10. dblink">Up</a></td><th width="60%" align="center">F.10. dblink</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="dict-int.html" title="F.11. dict_int">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="CONTRIB-DBLINK-BUILD-SQL-UPDATE"><div class="titlepage"></div><a id="id-1.11.7.19.23.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">dblink_build_sql_update</span></h2><p>dblink_build_sql_update — builds an UPDATE statement using a local tuple, replacing
the primary key field values with alternative supplied values
</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
dblink_build_sql_update(text relname,
int2vector primary_key_attnums,
integer num_primary_key_atts,
text[] src_pk_att_vals_array,
text[] tgt_pk_att_vals_array) returns text
</pre></div><div class="refsect1" id="id-1.11.7.19.23.5"><h2>Description</h2><p>
<code class="function">dblink_build_sql_update</code> can be useful in doing selective
replication of a local table to a remote database. It selects a row
from the local table based on primary key, and then builds a SQL
<code class="command">UPDATE</code> command that will duplicate that row, but with
the primary key values replaced by the values in the last argument.
(To make an exact copy of the row, just specify the same values for
the last two arguments.) The <code class="command">UPDATE</code> command always assigns
all fields of the row — the main difference between this and
<code class="function">dblink_build_sql_insert</code> is that it's assumed that
the target row already exists in the remote table.
</p></div><div class="refsect1" id="id-1.11.7.19.23.6"><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>relname</code></em></span></dt><dd><p>
Name of a local relation, for example <code class="literal">foo</code> or
<code class="literal">myschema.mytab</code>. Include double quotes if the
name is mixed-case or contains special characters, for
example <code class="literal">"FooBar"</code>; without quotes, the string
will be folded to lower case.
</p></dd><dt><span class="term"><em class="parameter"><code>primary_key_attnums</code></em></span></dt><dd><p>
Attribute numbers (1-based) of the primary key fields,
for example <code class="literal">1 2</code>.
</p></dd><dt><span class="term"><em class="parameter"><code>num_primary_key_atts</code></em></span></dt><dd><p>
The number of primary key fields.
</p></dd><dt><span class="term"><em class="parameter"><code>src_pk_att_vals_array</code></em></span></dt><dd><p>
Values of the primary key fields to be used to look up the
local tuple. Each field is represented in text form.
An error is thrown if there is no local row with these
primary key values.
</p></dd><dt><span class="term"><em class="parameter"><code>tgt_pk_att_vals_array</code></em></span></dt><dd><p>
Values of the primary key fields to be placed in the resulting
<code class="command">UPDATE</code> command. Each field is represented in text form.
</p></dd></dl></div></div><div class="refsect1" id="id-1.11.7.19.23.7"><h2>Return Value</h2><p>Returns the requested SQL statement as text.</p></div><div class="refsect1" id="id-1.11.7.19.23.8"><h2>Notes</h2><p>
As of <span class="productname">PostgreSQL</span> 9.0, the attribute numbers in
<em class="parameter"><code>primary_key_attnums</code></em> are interpreted as logical
column numbers, corresponding to the column's position in
<code class="literal">SELECT * FROM relname</code>. Previous versions interpreted the
numbers as physical column positions. There is a difference if any
column(s) to the left of the indicated column have been dropped during
the lifetime of the table.
</p></div><div class="refsect1" id="id-1.11.7.19.23.9"><h2>Examples</h2><pre class="screen">
SELECT dblink_build_sql_update('foo', '1 2', 2, '{"1", "a"}', '{"1", "b"}');
dblink_build_sql_update
-------------------------------------------------------------
UPDATE foo SET f1='1',f2='b',f3='1' WHERE f1='1' AND f2='b'
(1 row)
</pre></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="contrib-dblink-build-sql-delete.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="dblink.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="dict-int.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">dblink_build_sql_delete </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> F.11. dict_int</td></tr></table></div></body></html>
