SELECT
Output Columns
The rules given in the preceding sections will result in assignment
of non-unknown
data types to all expressions in a SQL query,
except for unspecified-type literals that appear as simple output
columns of a SELECT
command. For example, in
SELECT 'Hello World';
there is nothing to identify what type the string literal should be
taken as. In this situation LightDB will fall back
to resolving the literal's type as text
.
When the SELECT
is one arm of a UNION
(or INTERSECT
or EXCEPT
) construct, or when it
appears within INSERT ... SELECT
, this rule is not applied
since rules given in preceding sections take precedence. The type of an
unspecified-type literal can be taken from the other UNION
arm
in the first case, or from the destination column in the second case.
RETURNING
lists are treated the same as SELECT
output lists for this purpose.