Problem in my package procedure in a select query

Question

    PROCEDURE PROCESS_ROW( P_Event             IN VARCHAR2,
                           P_Old_Record_Key    IN VARCHAR2,
                           P_Ledger_Id         IN VARCHAR2,
                           P_Reference         IN VARCHAR2,
                           P_Fund              IN VARCHAR2) IS
    l_cash_txn_id   PF_CASH_TXNS.CASH_TXN_ID%TYPE;
    l_client_id     PF_CASH_TXNS.CLIENT_ID%TYPE;
    l_plan_id       PF_CASH_TXNS.PLAN_ID%TYPE;
    l_account       VARCHAR2(1);
    l_plan_id       VARCHAR2(100);
    BEGIN
        l_cash_txn_id := P_Ledger_Id;
        l_client_id := SUBSTR(P_Reference, -6);
        l_account := SUBSTR(P_Reference, 1, 1); -- Get first letter of reference code, this is the account type.
        SELECT PLAN_ID INTO l_plan_id FROM INTEGRATION.MAPPING WHERE account = l_account;
    END PROCESS_ROW;The problem is at this line:
SELECT PLAN_ID INTO l_plan_id FROM INTEGRATION.MAPPING WHERE account = l_account;
The error(s) I'm getting is:
PLS-00371: at most one declaration for 'L_PLAN_ID' is permitted
PL/SQL: ORA-00904: : invalid identifier
The INTEGRATION.MAPPING table is currently empty, I'm not sure if this would have anything to do with it?

Answer 1

Should be more or less self-explanatory:
In your first question, the code sample shows that you've declared L_PLAN_ID twice and the error message states:
"PLS-00371: at most one declaration for 'L_PLAN_ID' is permitted"
So, although datatype or length for your variables may differ, you still cannot use the same name for a variable more than once in a PL/SQL block.