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

IF 1=1
	SELECT 1
ELSE
	SELECT 0
-- returns 1

-- Definition
IF Boolean_expression   
     { sql_statement | statement_block }   
[ ELSE   
     { sql_statement | statement_block } ]