warning : function created with compilation error - sql

Question

Table EMP has ENAME as attribute.The following function gives error:
SET SERVEROUTPUT ON
SET ECHO ON
CREATE OR REPLACE FUNCTION count_emp(e_name varchar(20))
RETURN integer IS
total integer;
BEGIN
SELECT count(*) into total
FROM DEPARTMENTS
where ENAME = e_name;
RETURN total;
END;
/
warning:function created with compilation error.

Answer 1

You can run show errors; to see what compilation errors are.
The parameter's datatype should be specified without length. Also, use varchar2 instead of varchar.
From Oracle site:
The VARCHAR datatype is synonymous with the VARCHAR2 datatype. To avoid possible changes in behavior, always use the VARCHAR2 datatype to store variable-length character strings.
Try this:
CREATE OR REPLACE FUNCTION count_emp(e_name varchar2) -- here
RETURN integer IS
total integer;
BEGIN
SELECT count(*) into total
FROM DEPARTMENTS
where ENAME = e_name;
RETURN total;
END;
/

Answer 2

If you care about table EMP, you should use it in the function.
I would write this as:
CREATE OR REPLACE FUNCTION count_emp (
in_e_name varchar2
)
RETURN integer IS
v_total integer;
BEGIN
SELECT COUNT(*) into v_total
FROM EMP e
WHERE e.ENAME = in_e_name;
RETURN v_total;
END;
Notes:
Oracle will compile functions and stored procedures even when the objects don't (yet) exist. This is considered a "feature".
Use naming conventions to distinguish parameters and variables from columns. This is using in_ for the input parameters and v_ for the local variables.
Qualify all column name references. This further reduces the possibility of collision between a variable and column name.
You don't need a length for varchar2() inputs (which is preferable to varchar(), although perhaps one day, Oracle will cave to the standard).