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VALUES() SQL Commands VALUES()
NAME
VALUES - compute a set of rows
SYNOPSIS
VALUES ( expression [, ...] ) [, ...]
[ ORDER BY sort_expression [ ASC | DESC | USING operator ] [, ...] ]
[ LIMIT { count | ALL } ]
[ OFFSET start ]
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, 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 prac-
tical 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 con-
stants, 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, except that LIMIT and OFFSET are PostgreSQL exten-
sions.
SEE ALSO
INSERT [insert(7)], SELECT [select(l)]
SQL - Language Statements 2011-09-22 VALUES()
Generated by $Id: phpMan.php,v 4.49 2006/02/26 13:18:18 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2012-05-26 04:39 @38.107.179.237 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)