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><H1
><A
NAME="SQL-COMMENT"
>COMMENT</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN23309"
></A
><H2
>Name</H2
>COMMENT -- Adds a comment to an object within the database.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN23312"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>COMMENT ON
[
[ DATABASE | INDEX | RULE | SEQUENCE | TABLE | TYPE | VIEW ] <TT
CLASS="REPLACEABLE"
><I
>object_name</I
></TT
> |
COLUMN <TT
CLASS="REPLACEABLE"
><I
>table_name</I
></TT
>.<TT
CLASS="REPLACEABLE"
><I
>column_name</I
></TT
> |
FUNCTION <TT
CLASS="REPLACEABLE"
><I
>func_name</I
></TT
> ( <TT
CLASS="REPLACEABLE"
><I
>argument</I
></TT
> [, ...] ) |
AGGREGATE <TT
CLASS="REPLACEABLE"
><I
>aggr_func</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>aggr_type</I
></TT
> |
OPERATOR <TT
CLASS="REPLACEABLE"
><I
>operator</I
></TT
> ( <TT
CLASS="REPLACEABLE"
><I
>left_type</I
></TT
> , <TT
CLASS="REPLACEABLE"
><I
>right_type</I
></TT
> ) |
TRIGGER <TT
CLASS="REPLACEABLE"
><I
>trigger_name</I
></TT
> ON <TT
CLASS="REPLACEABLE"
><I
>table_name</I
></TT
>
] IS <TT
CLASS="REPLACEABLE"
><I
>'text'</I
></TT
></PRE
><DIV
CLASS="REFSECT2"
><A
NAME="R2-SQL-COMMENT-1"
></A
><H3
>Parameters</H3
><P
> <P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>DATABASE | INDEX | RULE | SEQUENCE | TABLE | TYPE | VIEW</TT
></DT
><DD
><P
>The type of database object that you are adding a comment to.</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>object_name</I
></TT
></DT
><DD
><P
>The name of the object (<TT
CLASS="LITERAL"
>database</TT
>, <TT
CLASS="LITERAL"
>index</TT
>, <TT
CLASS="LITERAL"
>rule</TT
>, <TT
CLASS="LITERAL"
>sequence</TT
>, <TT
CLASS="LITERAL"
>table</TT
>, <TT
CLASS="LITERAL"
>type</TT
>, or <TT
CLASS="LITERAL"
>view</TT
>) to which you are adding a comment.</P
></DD
><DT
><TT
CLASS="LITERAL"
>COLUMN</TT
> <TT
CLASS="REPLACEABLE"
><I
>table_name.column_name</I
></TT
></DT
><DD
><P
>The column name within <TT
CLASS="REPLACEABLE"
><I
>table_name</I
></TT
> you are adding a comment to. </P
></DD
><DT
><TT
CLASS="LITERAL"
>FUNCTION</TT
> <TT
CLASS="REPLACEABLE"
><I
>func_name</I
></TT
> <TT
CLASS="LITERAL"
>(</TT
> <TT
CLASS="REPLACEABLE"
><I
>argument</I
></TT
> <TT
CLASS="LITERAL"
>[, ...] )</TT
></DT
><DD
><P
>The name of the function on which you are commenting, specified also by the argument data types that it accepts.</P
></DD
><DT
><TT
CLASS="LITERAL"
>AGGREGATE</TT
> <TT
CLASS="REPLACEABLE"
><I
>aggr_func aggr_type</I
></TT
></DT
><DD
><P
>The aggregate function name (and associated data type <TT
CLASS="REPLACEABLE"
><I
>aggr_type</I
></TT
>, which it accepts) to which you are adding a comment.</P
></DD
><DT
><TT
CLASS="LITERAL"
>OPERATOR</TT
> <TT
CLASS="REPLACEABLE"
><I
>operator</I
></TT
> ( <TT
CLASS="REPLACEABLE"
><I
>left_type</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>right_type</I
></TT
> )</DT
><DD
><P
>The name of the operator on which you are commenting (<TT
CLASS="REPLACEABLE"
><I
>operator</I
></TT
>), further described by the data type it operates on to the left, and the data type it operates on to the right, separated by a comma, enclosed within parentheses. If either side is inapplicable, the <TT
CLASS="LITERAL"
>NONE</TT
> keyword may be used.</P
></DD
><DT
><TT
CLASS="LITERAL"
>TRIGGER</TT
> <TT
CLASS="REPLACEABLE"
><I
>trigger_name ON table_name</I
></TT
></DT
><DD
><P
>The name of the trigger on which you are placing a comment, and the name of the table upon which the trigger is placed.</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>text</I
></TT
></DT
><DD
><P
>The actual text of the comment to add.</P
></DD
></DL
></DIV
>
</P
></DIV
><DIV
CLASS="REFSECT2"
><A
NAME="R2-SQL-COMMENT-2"
></A
><H3
>Results</H3
><P
> <P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>COMMENT</TT
></DT
><DD
><P
>The message returned when an object is successfully commented.</P
></DD
></DL
></DIV
>
</P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="R1-SQL-COMMENT-1"
></A
><H2
>Description</H2
><P
><TT
CLASS="LITERAL"
>COMMENT</TT
> is a PostgreSQL-specific command that allows you to add comments to most objects within a database, including a database itself. Comments can be retrieved by using the following commands from within the <SPAN
><I
CLASS="EMPHASIS"
>psql</I
></SPAN
> client: </P
><P
> <P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>\l+</TT
></DT
><DD
><P
> Displays all databases available, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\dd</TT
></DT
><DD
><P
> Displays <SPAN
><I
CLASS="EMPHASIS"
>all</I
></SPAN
> database objects, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\d+</TT
></DT
><DD
><P
> Displays all database objects in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\dt+</TT
></DT
><DD
><P
> Displays all tables in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\di+</TT
></DT
><DD
><P
> Displays all indices in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\ds+</TT
></DT
><DD
><P
> Displays all sequences in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\dv+</TT
></DT
><DD
><P
> Displays all views in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\df+</TT
></DT
><DD
><P
> Displays all functions in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\da+</TT
></DT
><DD
><P
> Displays all aggregate functions in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\do+</TT
></DT
><DD
><P
> Displays all operators in the connected database, with comments.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>\dT+</TT
></DT
><DD
><P
> Displays all data types in the connected database, with comments.
</P
></DD
></DL
></DIV
>
</P
><P
>You can remove a comment by setting its <TT
CLASS="REPLACEABLE"
><I
>text</I
></TT
> to <TT
CLASS="LITERAL"
>NULL</TT
>.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>A comment that has been made on an object will be removed when that object is removed from the system.</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="R1-SQL-COMMENT-2"
></A
><H2
>Examples</H2
><P
>The following example adds a comment to the <TT
CLASS="LITERAL"
>customers</TT
> table:</P
><PRE
CLASS="SCREEN"
>booktown=# <TT
CLASS="USERINPUT"
><B
>COMMENT ON TABLE customers IS 'For customer names.';</B
></TT
>
COMMENT</PRE
><P
>The next example deletes the previously added comment from the <TT
CLASS="LITERAL"
>customer</TT
> table:</P
><PRE
CLASS="SCREEN"
>booktown=# <TT
CLASS="USERINPUT"
><B
>COMMENT ON TABLE customers IS NULL</B
></TT
>;</PRE
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