1COMMENT() SQL Commands COMMENT()
2
6 COMMENT - define or change the comment of an object
7
10 COMMENT ON
11 {
12 TABLE object_name |
13 COLUMN table_name.column_name |
14 AGGREGATE agg_name (agg_type [, ...] ) |
15 CAST (sourcetype AS targettype) |
16 CONSTRAINT constraint_name ON table_name |
17 CONVERSION object_name |
18 DATABASE object_name |
19 DOMAIN object_name |
20 FUNCTION func_name ( [ [ argmode ] [ argname ] argtype [, ...] ] ) |
21 INDEX object_name |
22 LARGE OBJECT large_object_oid |
23 OPERATOR op (leftoperand_type, rightoperand_type) |
24 OPERATOR CLASS object_name USING index_method |
25 [ PROCEDURAL ] LANGUAGE object_name |
26 ROLE object_name |
27 RULE rule_name ON table_name |
28 SCHEMA object_name |
29 SEQUENCE object_name |
30 TABLESPACE object_name |
31 TRIGGER trigger_name ON table_name |
32 TYPE object_name |
33 VIEW object_name
34 } IS 'text'
35
38 COMMENT stores a comment about a database object.
39 To modify a comment, issue a new COMMENT command for the same object.
41 Only one comment string is stored for each object. To remove a com‐
42 ment, write NULL in place of the text string. Comments are automati‐
43 cally dropped when the object is dropped.
44 Comments can be easily retrieved with the psql commands \dd, \d+, and
46 \l+. Other user interfaces to retrieve comments can be built atop the
47 same built-in functions that psql uses, namely obj_description,
48 col_description, and shobj_description (see in the documentation).
49
51 object_name
52 table_name.column_name
54 agg_name
56 constraint_name
58 func_name
60 op
62 rule_name
64 trigger_name
66 The name of the object to be commented. Names of tables, aggre‐
67 gates, domains, functions, indexes, operators, operator classes,
68 sequences, types, and views may be schema-qualified.
69 agg_type
71 An input data type on which the aggregate function operates. To
72 reference a zero-argument aggregate function, write * in place
73 of the list of input data types.
74 sourcetype
76 The name of the source data type of the cast.
77 targettype
79 The name of the target data type of the cast.
80 argmode
82 The mode of a function argument: either IN, OUT, or INOUT. If
83 omitted, the default is IN. Note that COMMENT ON FUNCTION does
84 not actually pay any attention to OUT arguments, since only the
85 input arguments are needed to determine the function's identity.
86 So it is sufficient to list the IN and INOUT arguments.
87 argname
89 The name of a function argument. Note that COMMENT ON FUNCTION
90 does not actually pay any attention to argument names, since
91 only the argument data types are needed to determine the func‐
92 tion's identity.
93 argtype
95 The data type(s) of the function's arguments (optionally schema-
96 qualified), if any.
97 large_object_oid
99 The OID of the large object.
100 PROCEDURAL
102 This is a noise word.
103 text The new comment, written as a string literal; or NULL to drop
105 the comment.
106
108 There is presently no security mechanism for comments: any user con‐
109 nected to a database can see all the comments for objects in that data‐
110 base (although only superusers can change comments for objects that
111 they don't own). For shared objects such as databases, roles, and
112 tablespaces comments are stored globally and any user connected to any
113 database can see all the comments for shared objects. Therefore, don't
114 put security-critical information in comments.
115
117 Attach a comment to the table mytable:
118 COMMENT ON TABLE mytable IS 'This is my table.';
120 Remove it again:
122 COMMENT ON TABLE mytable IS NULL;
124 Some more examples:
127 COMMENT ON AGGREGATE my_aggregate (double precision) IS 'Computes sample variance';
129 COMMENT ON CAST (text AS int4) IS 'Allow casts from text to int4';
130 COMMENT ON COLUMN my_table.my_column IS 'Employee ID number';
131 COMMENT ON CONVERSION my_conv IS 'Conversion to UTF8';
132 COMMENT ON DATABASE my_database IS 'Development Database';
133 COMMENT ON DOMAIN my_domain IS 'Email Address Domain';
134 COMMENT ON FUNCTION my_function (timestamp) IS 'Returns Roman Numeral';
135 COMMENT ON INDEX my_index IS 'Enforces uniqueness on employee ID';
136 COMMENT ON LANGUAGE plpython IS 'Python support for stored procedures';
137 COMMENT ON LARGE OBJECT 346344 IS 'Planning document';
138 COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two texts';
139 COMMENT ON OPERATOR - (NONE, text) IS 'This is a prefix operator on text';
140 COMMENT ON OPERATOR CLASS int4ops USING btree IS '4 byte integer operators for btrees';
141 COMMENT ON ROLE my_role IS 'Administration group for finance tables';
142 COMMENT ON RULE my_rule ON my_table IS 'Logs updates of employee records';
143 COMMENT ON SCHEMA my_schema IS 'Departmental data';
144 COMMENT ON SEQUENCE my_sequence IS 'Used to generate primary keys';
145 COMMENT ON TABLE my_schema.my_table IS 'Employee Information';
146 COMMENT ON TABLESPACE my_tablespace IS 'Tablespace for indexes';
147 COMMENT ON TRIGGER my_trigger ON my_table IS 'Used for RI';
148 COMMENT ON TYPE complex IS 'Complex number data type';
149 COMMENT ON VIEW my_view IS 'View of departmental costs';
150
153 There is no COMMENT command in the SQL standard.
154SQL - Language Statements 2008-06-08 COMMENT()