mysql多个字段in查询```jsSELECT 　　 * FROM 　　 test WHERE 　　 ( `a` =

	　　 * 
FROM
	　　 test 
WHERE
	　　 ( `a` = 1 AND `b` = 2 ) 
	OR 　( `a` = 3 AND `b` = 4 ) 
	OR 　( `a` = 5 AND `b` = 6 ) 
	OR 　( `a` = 9 AND `b` = 10 );
 

#优化后： 
SELECT
　　 * 
FROM
	　　 test 
WHERE
	　　 ( a, b ) IN (( 1, 2 ),( 3, 4 ),( 5, 6 ),( 9, 10 ));
 

#或者
SELECT
　* 
FROM
	　　 test 
WHERE
	　　 ( a, b ) IN (SELECT a, b FROM test2);