VALUES
Synopsis
VALUES (expression [, ...] ) [, ...] [ ORDER BYsort_expression [ ASC | DESC | USINGoperator ] [, ...] ] [ LIMIT {count | ALL } ] [ OFFSETstart [ ROW | ROWS ] ] [ FETCH { FIRST | NEXT } [count ] { ROW | ROWS } ONLY ]Description
VALUES computes a row value or set of row values specified by value expressions. It is most commonly used to generate a"constant table" within a larger command, but it can be used on its own.
When more than one row is specified, all the rows must have the same number of elements. The data types of the resulting table's columns are determined by combining the explicit or inferred types of the expressions appearing in that column, using the same rules as forUNION (seeSection 10.5).
Within larger commands,VALUES is syntactically allowed anywhere thatSELECT is. Because it is treated like aSELECT by the grammar, it is possible to use theORDER BY,LIMIT (or equivalentlyFETCH FIRST), andOFFSET clauses with aVALUES command.
Parameters
- expression
A constant or expression to compute and insert at the indicated place in the resulting table (set of rows). In aVALUES list appearing at the top level of anINSERT, anexpression can be replaced byDEFAULT to indicate that the destination column's default value should be inserted.DEFAULT cannot be used whenVALUES appears in other contexts.
- sort_expression
An expression or integer constant indicating how to sort the result rows. This expression can refer to the columns of theVALUES result ascolumn1,column2, etc. For more details seeORDER BY Clause.
- operator
A sorting operator. For details seeORDER BY Clause.
- count
The maximum number of rows to return. For details seeLIMIT Clause.
- start
The number of rows to skip before starting to return rows. For details seeLIMIT Clause.
Notes
VALUES lists with very large numbers of rows should be avoided, as you might encounter out-of-memory failures or poor performance.VALUES appearing withinINSERT is a special case (because the desired column types are known from theINSERT's target table, and need not be inferred by scanning theVALUES list), so it can handle larger lists than are practical in other contexts.
Examples
A bareVALUES command:
VALUES (1, 'one'), (2, 'two'), (3, 'three');
This will return a table of two columns and three rows. It's effectively equivalent to:
SELECT 1 AS column1, 'one' AS column2UNION ALLSELECT 2, 'two'UNION ALLSELECT 3, 'three';
More usually,VALUES is used within a larger SQL command. The most common use is inINSERT:
INSERT INTO films (code, title, did, date_prod, kind) VALUES ('T_601', 'Yojimbo', 106, '1961-06-16', 'Drama');In the context ofINSERT, entries of aVALUES list can beDEFAULT to indicate that the column default should be used here instead of specifying a value:
INSERT INTO films VALUES ('UA502', 'Bananas', 105, DEFAULT, 'Comedy', '82 minutes'), ('T_601', 'Yojimbo', 106, DEFAULT, 'Drama', DEFAULT);VALUES can also be used where a sub-SELECT might be written, for example in aFROM clause:
SELECT f.* FROM films f, (VALUES('MGM', 'Horror'), ('UA', 'Sci-Fi')) AS t (studio, kind) WHERE f.studio = t.studio AND f.kind = t.kind;UPDATE employees SET salary = salary * v.increase FROM (VALUES(1, 200000, 1.2), (2, 400000, 1.4)) AS v (depno, target, increase) WHERE employees.depno = v.depno AND employees.sales >= v.target;Note that anAS clause is required whenVALUES is used in aFROM clause, just as is true forSELECT. It is not required that theAS clause specify names for all the columns, but it's good practice to do so. (The default column names forVALUES arecolumn1,column2, etc inPostgreSQL, but these names might be different in other database systems.)
WhenVALUES is used inINSERT, the values are all automatically coerced to the data type of the corresponding destination column. When it's used in other contexts, it might be necessary to specify the correct data type. If the entries are all quoted literal constants, coercing the first is sufficient to determine the assumed type for all:
SELECT * FROM machinesWHERE ip_address IN (VALUES('192.168.0.1'::inet), ('192.168.0.10'), ('192.168.1.43'));Tip: For simpleIN tests, it's better to rely on the list-of-scalars form ofIN than to write aVALUES query as shown above. The list of scalars method requires less writing and is often more efficient.
Compatibility
VALUES conforms to the SQL standard.LIMIT andOFFSET arePostgreSQL extensions; see also underSELECT.