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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 V1.79.1" /><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 12.4 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>
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