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This is a docs patch to go with my DROP CONSTRAINT patch.

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Christopher Kings
This commit is contained in:
Bruce Momjian 2001-05-30 13:01:08 +00:00
parent 7160c86ec2
commit 3d56fb7598
1 changed files with 33 additions and 30 deletions
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63
doc/src/sgml/ref/alter_table.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.24 2001/05/09 13:27:15 momjian Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.25 2001/05/30 13:01:08 momjian Exp $
Postgres documentation
-->
@ -38,6 +38,8 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
RENAME TO <replaceable class="PARAMETER">newtable</replaceable>
ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
ADD <replaceable class="PARAMETER">table constraint definition</replaceable>
ALTER TABLE [ ONLY ] <replaceable class="PARAMETER">table</replaceable>
DROP CONSTRAINT <replaceable class="PARAMETER">constraint</replaceable> { RESTRICT | CASCADE }
ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
OWNER TO <replaceable class="PARAMETER">new owner</replaceable>
</synopsis>
@ -177,6 +179,8 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
The ADD <replaceable class="PARAMETER">table constraint definition</replaceable> clause
adds a new constraint to the table using the same syntax as <xref
linkend="SQL-CREATETABLE" endterm="SQL-CREATETABLE-title">.
The DROP CONSTRAINT <replaceable class="PARAMETER">constraint</replaceable> clause
drops all CHECK constraints on the table (and its children) that match <replaceable class="PARAMETER">constraint</replaceable>.
The OWNER clause changes the owner of the table to the user <replaceable class="PARAMETER">
new user</replaceable>.
</para>
@ -208,11 +212,31 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
<para>
In the current implementation, only FOREIGN KEY and CHECK constraints can
be added to a table. To create or remove a unique constraint, create
be added to a table. To create a unique constraint, create
a unique index (see <xref linkend="SQL-CREATEINDEX"
endterm="SQL-CREATEINDEX-title">).
</para>
<para>
Currently only CHECK constraints can be dropped from a table. The RESTRICT
keyword is required, although dependencies are not checked. The CASCADE
option is unsupported. To remove a PRIMARY or UNIQUE constraint, drop the
relevant index using the <xref linkend="SQL-DROPINDEX" endterm="SQL-DROPINDEX-TITLE"> command.
To remove FOREIGN KEY constraints you need to recreate
and reload the table, using other parameters to the
<xref linkend="SQL-CREATETABLE" endterm="SQL-CREATETABLE-title">
command.
</para>
<para>
For example, to drop all constraints on a table <literal>distributors</literal>:
<programlisting>
CREATE TABLE temp AS SELECT * FROM distributors;
DROP TABLE distributors;
CREATE TABLE distributors AS SELECT * FROM temp;
DROP TABLE temp;
</programlisting>
</para>
<para>
You must own the table in order to change it.
Changing any part of the schema of a system
@ -260,6 +284,13 @@ ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5)
</programlisting>
</para>
<para>
To remove a check constraint from a table and all its children:
<programlisting>
ALTER TABLE distributors DROP CONSTRAINT zipchk
</programlisting>
</para>
<para>
To add a foreign key constraint to a table:
<programlisting>
@ -289,34 +320,6 @@ ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address) REFERENCES
statement which are not yet directly supported by <productname>Postgres</productname>:
<variablelist>
<varlistentry>
<term>
<synopsis>
ALTER TABLE <replaceable class="PARAMETER">table</replaceable> DROP CONSTRAINT <replaceable class="PARAMETER">constraint</replaceable> { RESTRICT | CASCADE }
</synopsis>
</term>
<listitem>
<para>
Removes a table constraint (such as a check constraint,
unique constraint, or foreign key constraint). To
remove a unique constraint, drop a unique index.
To remove other kinds of constraints you need to recreate
and reload the table, using other parameters to the
<xref linkend="SQL-CREATETABLE" endterm="SQL-CREATETABLE-title">
command.
</para>
<para>
For example, to drop any constraints on a table <literal>distributors</literal>:
<programlisting>
CREATE TABLE temp AS SELECT * FROM distributors;
DROP TABLE distributors;
CREATE TABLE distributors AS SELECT * FROM temp;
DROP TABLE temp;
</programlisting>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<synopsis>