if else in where clause sql code example

Example 1: else if sql server

IF (Expression 1)
BEGIN
   Statement 1;
END

ELSE IF (Expression 2)
BEGIN
   Statement 2;
END
..........
ELSE 
BEGIN
   Default Statement;
END

Example 2: sql if else

-- PL/SQL
BEGIN
    IF my_val = 1 THEN [...]
    ELSE [...]
    END IF;
END;
-- In a query (DUAL is for Oracle)
SELECT CASE WHEN my_col = 1 THEN 'Ok' ELSE 'Ko' END AS my_result
FROM DUAL;

Example 3: if else sql

IF Boolean_expression
BEGIN
    -- Statement block executes when the Boolean expression is TRUE
END
ELSE
BEGIN
    -- Statement block executes when the Boolean expression is FALSE
END