Oracle Error PLS-00399: different types of columns in UNION, INTERSECT, or MINUS expression

Oracle Error Message

PLS-00399: different types of columns in UNION, INTERSECT, or MINUS expression

Reason for the Error

The select lists to the left and right of a UNION, INTERSECT, or MINUS expression select at least one column that is mismatched in datatype. For example, the following statement is faulty because the constant 3 has datatype NUMBER, whereas SYSDATE has datatype DATE: CURSOR my_cur IS SELECT 3 FROM emp INTERSECT SELECT SYSDATE FROM emp;

Solution

Change the select lists so that they match in datatype. You might want to use datatype conversion functions in the select list of one or more queries.