VALUES

VALUES

7

SQL - Language Statements

VALUES

compute a set of rows

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 [???](#typeconv-union-case)).

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
    [???](#sql-orderby) in the [???](#sql-select) documentation.

operator

:   A sorting operator. For details see [???](#sql-orderby) in the
    [???](#sql-select) documentation.

count

:   The maximum number of rows to return. For details see
    [???](#sql-limit) in the [???](#sql-select) documentation.

start

:   The number of rows to skip before starting to return rows. For
    details see [???](#sql-limit) in the [???](#sql-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 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](#functions-comparisons-in-scalar) 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 [???](#sql-select).

See Also
========
