NAME
VALUES - compute a set of rows
SYNOPSIS
VALUES ( expression [, ...] ) [, ...]
[ ORDER BY sort_expression [ ASC | DESC | USING operator ] [, ...] ]
[ LIMIT { count | ALL } ]
[ OFFSET start [ 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 in the documentation).
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
expression
A constant or expression to compute and insert at the indicated
place in the resulting table (set of rows). In a VALUES list
appearing at the top level of an INSERT, an expression can be
replaced by DEFAULT to indicate that the destination column’s
default value should be inserted. DEFAULT cannot be used when
VALUES 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 the
VALUES result as column1, column2, etc. For more details see
ORDER BY Clause [select(7)].
operator
A sorting operator. For details see ORDER BY Clause [select(7)].
count The maximum number of rows to return. For details see LIMIT
Clause [select(7)].
start The number of rows to skip before starting to return rows. For
details see LIMIT Clause [select(7)].
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 an AS clause is required when VALUES is used in a FROM
clause, just as is true for SELECT. It is not required that the AS
clause specify names for all the columns, but it’s good practice to do
so. (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 [select(7)].
SEE ALSO
INSERT [insert(7)], SELECT [select(7)]