VALUES
VALUES — compute a set of rows
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 for UNION
(see Section 10.5).
Within larger commands, VALUES is syntactically allowed
anywhere that SELECT is. Because it is treated like a
SELECT by the grammar, it is possible to use
the ORDER BY, LIMIT (or
equivalently FETCH FIRST),
and OFFSET clauses with a
VALUES command.
Parameters
expressionA constant or expression to compute and insert at the indicated place in the resulting table (set of rows). In a
VALUESlist appearing at the top level of anINSERT, anexpressioncan be replaced byDEFAULTto indicate that the destination column's default value should be inserted.DEFAULTcannot be used whenVALUESappears in other contexts.sort_expressionAn expression or integer constant indicating how to sort the result rows. This expression can refer to the columns of the
VALUESresult ascolumn1,column2, etc. For more details see ORDER BY Clause in the SELECT documentation.operatorA sorting operator. For details see ORDER BY Clause in the SELECT documentation.
countThe maximum number of rows to return. For details see LIMIT Clause in the SELECT documentation.
startThe number of rows to skip before starting to return rows. For details see LIMIT Clause in the SELECT documentation.
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 within INSERT is a special case
(because the desired column types are known from the INSERT's
target table, and need not be inferred by scanning the VALUES
list), so it can handle larger lists than are practical in other contexts.
Examples
A bare VALUES 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 column2 UNION ALL SELECT 2, 'two' UNION ALL SELECT 3, 'three';
More usually, VALUES is used within a larger SQL command.
The most common use is in INSERT:
INSERT INTO films (code, title, did, date_prod, kind)
VALUES ('T_601', 'Yojimbo', 106, '1961-06-16', 'Drama');
In the context of INSERT, entries of a VALUES list
can be DEFAULT 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 a FROM 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 if VALUES is used in a FROM
clause, a table alias is optional. Assigning alias names to the columns
of the VALUES list is optional, but is good practice.
(The default column names for VALUES are column1,
column2, etc. in PostgreSQL, but
these names might be different in other database systems.)
When VALUES is used in INSERT, 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 machines
WHERE ip_address IN (VALUES('192.168.0.1'::inet), ('192.168.0.10'), ('192.168.1.43'));
Tip
For simple IN tests, it's better to rely on the
list-of-scalars
form of IN than to write a VALUES
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 and OFFSET are
PostgreSQL extensions; see also
under SELECT.
Report a documentation issue
Read the upstream documentation. For corrections, first check the current manual.