oracle plsql concanting a variable to a string - oracle10g

Question

below is the program written in oracle plsql when this program is run by giving P_LOC value as 'DALLAS'
it gives error as -904 ORA-00904: "DALLAS": invalid identifier please provide a solution
create or replace
PROCEDURE PR_EMP_LST1
( P_LOC IN VARCHAR2
, P_MIN_SAL IN NUMBER
, P_MAX_SAL IN NUMBER
, P_REF_CUR OUT SYS_REFCURSOR
) AS
TYPE TY_LST_REFCURSOR IS REF CURSOR ;
cur_emp_lst TY_LST_REFCURSOR;
v_inv_query VARCHAR2(2000);
V_USG_CL VARCHAR2(200);
BEGIN
IF P_LOC IS NULL AND p_min_sal IS NULL AND p_max_sal IS NULL THEN
v_inv_query :='SELECT ENAME
FROM EMP ';
ELSE
v_inv_query :='SELECT ENAME
FROM EMP WHERE ';
IF P_LOC IS NULL AND p_min_sal IS NOT NULL AND p_max_sal IS NOT NULL THEN
v_inv_query :=v_inv_query ||' SAL BETWEEN '
||p_min_sal
||' AND '
|| p_max_sal;
-- v_inv_query :=v_inv_query ||' SAL BETWEEN :1 AND :2 ';
dbms_output.put_line('2');
-- V_USG_CL:= ' USING '||p_min_sal||' , '|| p_max_sal;
ELSIF P_LOC IS NOT NULL AND p_min_sal IS NOT NULL AND p_max_sal IS NOT NULL THEN
dbms_output.put_line('1');
v_inv_query :=v_inv_query||' SAL BETWEEN '
||p_min_sal || ' AND '|| p_max_sal
|| ' AND DEPTNO IN (SELECT DEPTNO
FROM DEPT
WHERE LOC= '
|| p_loc
||' )';
dbms_output.put_line('2');
ELSIF P_LOC IS NOT NULL AND p_min_sal IS NULL AND p_max_sal IS NOT NULL THEN
v_inv_query :=v_inv_query||' SAL <= '
||p_max_sal
||' AND DEPTNO IN (SELECT DEPTNO
FROM DEPT
WHERE LOC= '
|| p_loc
||' )';
ELSIF P_LOC IS NOT NULL AND p_min_sal IS NOT NULL AND p_max_sal IS NULL THEN
v_inv_query :=v_inv_query||' SAL >= '
||p_min_sal
||' AND DEPTNO IN (SELECT DEPTNO
FROM DEPT
WHERE LOC= '
||p_loc
||' )';
ELSIF P_LOC IS NULL AND p_min_sal IS NULL AND p_max_sal IS NOT NULL THEN
v_inv_query :=v_inv_query||' SAL <= '
||p_max_sal;
ELSIF P_LOC IS NULL AND p_min_sal IS NOT NULL AND p_max_sal IS NULL THEN
v_inv_query :=v_inv_query||' SAL >= '
|| p_min_sal;
ELSIF P_LOC IS NOT NULL AND p_min_sal IS NULL AND p_max_sal IS NULL THEN
v_inv_query :=v_inv_query||' DEPTNO IN (SELECT DEPTNO
FROM DEPT
WHERE LOC= '
||p_loc
||' )';
END IF;
END IF;
dbms_output.put_line('3');
dbms_output.put_line(v_inv_query );
OPEN cur_emp_lst FOR v_inv_query ;
dbms_output.put_line('4');
P_REF_CUR:=cur_emp_lst;
END PR_EMP_LST1;

Answer 1

'SELECT DEPTNO FROM DEPT WHERE LOC= ''' || p_loc ||''' )';
As Dallas is string, you need to handle it as string: 'DALLAS' and not as DALLAS. Inside of string you have to use ''

Answer 2

P_LOC parameter is string type, the parameter value should be enclosed within single quotes.
In existing dynamic SQL condition, the single quotes are not present.
Please replace below condition with new condition.
Existing Condition:
|| ' AND DEPTNO IN (SELECT DEPTNO FROM DEPT WHERE LOC= ' || p_loc ||' )';
New Condition:
|| q'[ AND DEPTNO IN (SELECT DEPTNO FROM DEPT WHERE LOC= ']' || p_loc || q'[' )]';
Thank you...