PLS-00204: function or pseudo-column string may be used inside a SQL statement only

PLS-00204: function or pseudo-column string may be used inside a SQL statement only

Cause: A pseudocolumn or proscribed function was used in a procedural statement. The SQL pseudocolumns (CURRVAL, LEVEL, NEXTVAL, ROWID, ROWNUM) can be used only in SQL statements. Likewise, certain functions such as DECODE, DUMP, and VSIZE and the SQL group functions (AVG, MIN, MAX, COUNT, SUM, STDDEV, VARIANCE) can be used only in SQL statements.

Action: Remove the pseudocolumn reference or function call from the procedural statement. Or, replace the procedural statement with a SELECT INTO statement; for example, replace bonus := DECODE(rating, 1, 5000, 2, 2500, ...); with the following statement: SELECT DECODE(rating, 1, 5000, 2, 2500, ...) INTO bonus FROM dual;