Dynamic PL SQL in where condition for different operands - sql

Question

I have three tables, viz:
Mains_Control
Control_Mapping
Control_Details
along with several conditions and columns. But I am performing dynamic operations on the tables columns given below.
I am unable to write a dynamic SQL block in PL-SQL procedure for the below conditions. Could anyone please assist me on this particular scenario.
SELECT *
FROM CUR_ALL_CONTENTS
WHERE MAINS_CONTROL SWITCH = $SWITCH
AND ($ATTRIB_COLUMNS = $ATTRIB_VAL
OR $ATTRIB_COLUMNS = $ATTRIB_VAL)
The above business condition is this
SELECT *
FROM CUR_ALL_CONTENTS
WHERE MAINS_CONTROL_SWITCH = 'TYPE'
AND (SWITCH_MODE = 'THRUST' OR SWITCH_MODE_GEAR = 'SEC_GEAR')
Here SWITCH attribute value can change, ATTRIB_COLUMNS and ATTRIB_VAL can change.
Mains_Control table has the following columns
SWITCH ACTION_CODE RULE_MAP_1
TYPE ON R1
TYPE OFF R2
METHOD HOLD R3
METHOD TERM_IN R4
Control_Mapping table has the following columns
RULE_MAP_1 RULE_MAP_2
R1 M11
R2 M22
R3 M33
R4 M44
Control_Details table has the following columns
RULE_MAP_2 ATTRIB_COLUMNS OPERAND ATTRIB_VAL
M11 SWTICH_MODE = THRUST
M22 SWITCH_MODE_GEAR = SEC_GEAR
M33 HOLD_RELEASE <> END

Answer 1

Still not clear for me how you determine which condition shall be used and when. Let's give this example with hard-coded rule set:
DECLARE
sqlstr VARCHAR2(30000);
cur INTEGER;
res INTEGER;
refCur SYS_REFCURSOR;
val Mains_Control.SWITCH%TYPE;
CURSOR Conditions IS
SELECT *
FROM RULE_MAP_2 IN ('M11', 'M22');
BEGIN
cur := DBMS_SQL.OPEN_CURSOR;
sqlstr := 'SELECT * '||CHR(13);
sqlstr := sqlstr || 'FROM CUR_ALL_CONTENTS '||CHR(13);
sqlstr := sqlstr || 'WHERE MAINS_CONTROL_SWITCH = :switch AND (';
FOR aCond IN Conditions LOOP
sqlstr := sqlstr || aCond.ATTRIB_COLUMNS ||aCond.OPERAND||' :'||RULE_MAP_2 ||' OR '
END LOOP;
sqlstr := REGEXP_REPLACE(sqlstr, ' OR ', ')');
DBMS_OUTPUT.PUT_LINE(sqlStr); --> verify generated statement
DBMS_SQL.PARSE(cur, sqlStr, DBMS_SQL.NATIVE);
SELECT SWITCH
INTO val
FROM Mains_Control
WHERE RULE_MAP_1 = 'R1';
DBMS_SQL.BIND_VARIABLE(cur, ':switch', sw);
FOR aCond IN Conditions LOOP
DBMS_SQL.BIND_VARIABLE(cur, ':'||aCond.RULE_MAP_2, aCond.ATTRIB_VAL);
END LOOP;
res := DBMS_SQL.EXECUTE(cur);
refCur := DBMS_SQL.TO_REFCURSOR(cur);
FETCH refCur BULK COLLECT INTO ...;
END;
The code would be simpler without DBMS_SQL.BIND_VARIABLE, however using bind variables is the proper way of doing it.