Implementing Operators

The SBtree indextype supports three operators. Each operator has a corresponding functional implementation. The functional implementations of the eq, gt and lt operators are presented next.

Create Functional Implementations

Functional Implementation of EQ (EQUALS)

The functional implementation for eq is provided by a function (bt_eq) that takes in two VARCHAR2 parameters and returns 1 if they are equal and 0 otherwise.

CREATE FUNCTION bt_eq(a VARCHAR2, b VARCHAR2) RETURN NUMBER AS
BEGIN 
  IF a = b then
    RETURN 1;
  ELSE
    RETURN 0;
  END IF;
END;

Functional Implementation of LT (LESS THAN)

The functional implementation for lt is provided by a function (lt_eq) that takes in two VARCHAR2 parameters and returns 1 if the first parameter is less than the second, 0 otherwise.

CREATE FUNCTION bt_lt(a VARCHAR2, b VARCHAR2) RETURN NUMBER AS
BEGIN 
  IF a < b then
    RETURN 1;
  ELSE
   RETURN 0;
  END IF;
END;

Functional Implementation of GT (GREATER THAN)

The functional implementation for gt is provided by a function (gt_eq) that takes in two VARCHAR2 parameters and returns 1 if the first parameter is greater than the second, 0 otherwise.

CREATE FUNCTION bt_gt(a VARCHAR2, b VARCHAR2) RETURN NUMBER AS
BEGIN 
  IF a > b then
    RETURN 1;
  ELSE
    RETURN 0;
  END IF;
END;

Create Operators

To create the operator, you need to specify the signature of the operator along with its return type and also its functional implementation.

Operator EQ

CREATE OPERATOR eq 
BINDING (VARCHAR2, VARCHAR2) RETURN NUMBER 
USING bt_eq;

Operator LT

CREATE OPERATOR lt 
BINDING (VARCHAR2, VARCHAR2) RETURN NUMBER 
USING bt_lt;

Operator GT

CREATE OPERATOR gt 
BINDING (VARCHAR2, VARCHAR2) RETURN NUMBER 
USING bt_gt;