diff options
| -rw-r--r-- | doc/src/sgml/ref/alter_table.sgml | 63 |
1 files changed, 33 insertions, 30 deletions
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml index 5649890bf8f..87252f74676 100644 --- a/doc/src/sgml/ref/alter_table.sgml +++ b/doc/src/sgml/ref/alter_table.sgml @@ -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 @@ -261,6 +285,13 @@ ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5) </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> ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address) REFERENCES addresses(address) MATCH FULL @@ -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> |