The COALESCE function
Derby Reference Manual
121
The COALESCE function takes two or more compatible arguments and returns the first
argument that is not null.
The result is null only if all the arguments are null.
If all the parameters of the function call are dynamic, an error occurs.
Note: A synonym for COALESCE is VALUE. VALUE is accepted by Derby but is not
recognized by the SQL standard.
Syntax
COALESCE ( expression, expression [, expression]* )
The function must have at least two arguments.
Example
ij> -- create table with three different integer types
ij> create table temp(smallintcol smallint, bigintcol bigint, intcol
integer);
0 rows inserted/updated/deleted
ij> insert into temp values (1, null, null);
1 row inserted/updated/deleted
ij> insert into temp values (null, 2, null);
1 row inserted/updated/deleted
ij> insert into temp values (null, null, 3);
1 row inserted/updated/deleted
ij> select * from temp;
SMALL&|BIGINTCOL |INTCOL
---------------------------------------
1 |NULL |NULL
NULL |2 |NULL
NULL |NULL |3
3 rows selected
ij> -- the return data type of coalesce is bigint
ij> select coalesce (smallintcol, bigintcol) from temp;
1
--------------------
1
2
NULL
3 rows selected
ij> -- the return data type of coalesce is bigint
ij> select coalesce (smallintcol, bigintcol, intcol) from temp;
1
--------------------
1
2
3
3 rows selected
ij> -- the return data type of coalesce is integer
ij> select coalesce (smallintcol, intcol) from temp;
1
-----------
1
NULL
3
3 rows selected
