Expected CHAR got NUMBER - oracle

Question

DB: Oracle 11g
Query:
SELECT CASE
WHEN rs.OPTION = '3'
THEN
(SELECT COUNT(DISTINCT ex.EXTS) AS TMPCOL0
FROM CRSIDM.SUB_OPTS ex
INNER JOIN CRSIDM.SUB_OPTS_GRP cg
ON cg.GROUP_ID = ex.GRP_ID
)
ELSE
(SELECT COUNT(DISTINCT ex.EXTS) AS TMPCOL0
FROM CRSIDM.SUB_OPTS ex
INNER JOIN CRSIDM.SUB_OPTS_POL cg
ON cg.GROUP_ID = ex.GRP_ID
)
END AS PROPTS
FROM PR_OPTS
I am getting error 'expected CHAR got NUMBER', here EXTS,GROUP_ID & GRP_ID are numeric. Then how there is a chance of expecting CHAR?

Answer 1

Generally when Oracle compares different datatypes such as a NUMBER with a CHARACTER, implicit conversion kicks in and all is well (provided the data can be converted.) For example, if you have a function that expects a CHARACTER value but you pass it a NUMBER, all is well - Oracle simply converts the NUMBER to character.
E.g. a function like this:
create or replace function get_something(p_id VARCHAR2) return number ...
works if you call it with this:
get_dno(10);
or this:
get_dno('10');
and in SQL:
select * from some_table where numeric_column = '10' -- no problem.
A popular place where you see this kind of error is with the return values in CASE statements. For instance, you'll get that error if you have something like this:
SQL> SELECT CASE WHEN 1 = 1 THEN '1' ELSE 2 END
2 FROM dual
3 ;
SELECT CASE WHEN 1 = 1 THEN '1' ELSE 2 END
*
ERROR at line 1:
ORA-00932: inconsistent datatypes: expected CHAR got NUMBER
(The datatype from the first WHEN clause is what it expects in the other WHEN/ELSE clauses that follow.)
But in your case the WHEN and THEN both return counts - the datatypes are consistent. So, I think you have a red-herring in there.
As Alex mentioned above, OPTION is a keyword and if you try and create a table with that as a column name, Oracle disagrees:
SQL> create table dummy
2 (option varchar2(10)
3 );
(option varchar2(10)
*
ERROR at line 2:
ORA-00904: : invalid identifier
This works:
SQL> create table dummy
2 (option_col varchar2(10)
3 );
Table created.
or you could do it with quotes:
SQL> create table dummy
2 ("option" varchar2(10));
Table created.
But now you're in a world of hurt - you need quotes from now on:
SQL> select option from dummy;
select option from dummy
*
ERROR at line 1:
ORA-00936: missing expression
SQL> select d.option from dummy d;
select d.option from dummy d
*
ERROR at line 1:
ORA-01747: invalid user.table.column, table.column, or column specification
With quotes:
SQL> select d."option" from dummy d;
no rows selected
So, if your query is really giving you "expected CHAR, got NUMBER", it looks to me like something is off.

Answer 2

Essentially, it means some of the fields you are using aren't compatible with each other. It's basically a "type mismatch". Just check to see if any types of CHAR are being used with types of NUMBER. Then you can either switch the type of one, or simply use a conversion as part of the query.

Answer 3

The issue is OPTION = '3', the quotation marks indicate that you're looking for a string containing the solitary character 3.
Try this instead:
SELECT CASE
WHEN rs.OPTION = 3
THEN
(SELECT COUNT(DISTINCT ex.EXTS) AS TMPCOL0
FROM CRSIDM.SUB_OPTS ex
INNER JOIN CRSIDM.SUB_OPTS_GRP cg
ON cg.GROUP_ID = ex.GRP_ID)
ELSE
(SELECT COUNT(DISTINCT ex.EXTS) AS TMPCOL0
FROM CRSIDM.SUB_OPTS ex
INNER JOIN CRSIDM.SUB_OPTS_POL cg
ON cg.GROUP_ID = ex.GRP_ID)
END AS PROPTS
FROM PR_OPTS