VALUES
Synopsis
Use the VALUES
statement to generate a row set specified as an explicitly written set of explicitly written tuples.
Syntax
values ::= VALUES ( expression_list ) [ ,(expression_list ... ]
[ ORDER BY { order_expr [ , ... ] } ]
[ LIMIT { int_expression | ALL } ]
[ OFFSET int_expression [ ROW | ROWS ] ]
[ FETCH { FIRST | NEXT } int_expression { ROW | ROWS } ONLY ]
expression_list ::= expression [ , ... ]
values
expression_list
Semantics
expression_list
A comma separated list of parenthesized expression lists. The degenerate form is just a single constant, thus:
values ('dog'::text);
This is the result:
column1
---------
dog
The result has as many columns named "column1", "column2", ... "columnN" as there are expressions in the expression list, thus:
values
(1::int, '2019-06-25 12:05:30'::timestamp, 'dog'::text),
(2::int, '2020-07-30 13:10:45'::timestamp, 'cat'::text);
This is the result:
column1 | column2 | column3
---------+---------------------+---------
1 | 2019-06-25 12:05:30 | dog
2 | 2020-07-30 13:10:45 | cat
If an expression is written without a typecast, then its data type is inferred. For example, 'dog' is inferred to have data type text
and 4.2 is inferred to have data type numeric
.
Each successive parenthesized expression list must specify the same number of expressions with the same data types. Try this counter example:
values
(1::int, '2019-06-25 12:05:30'::timestamp, 'dog'::text),
(2::int, '2020-07-30 13:10:45'::timestamp, 'cat'::text, 42::int);
It causes this error:
42601: VALUES lists must all be the same length
And try this counter example:
values (1::int), ('x'::text);
It causes this error:
42804: VALUES types integer and text cannot be matched
The ORDER BY, LIMIT, OFFSET, and FETCH clauses
These clauses have the same semantics when they are used in a VALUES
statement as they do when they are used in a SELECT
statement.
Example
A VALUES
statement can be used as a subquery by surrounding it with parentheses, and giving this an alias, in just the same way that a SELECT
statement can be so surrounded and so used. Try this first:
select chr(v) as c from (
select * from generate_series(97, 101)
) as t(v);
This is the result:
c
---
a
b
c
d
e
Now use a VALUES
statement (on line #2) within the parentheses instead of the SELECT
statement:
select chr(v) as c from (
values (100), (111), (103)
) as t(v);
This is the result:
c
---
d
o
g