MySQL，排序，统计行转列

DROP TABLE IF EXISTS `a`;
CREATE TABLE `a` (
  `type` varchar(255) DEFAULT NULL,
  `name` varchar(255) DEFAULT NULL,
  `val` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `a` VALUES (‘x‘, ‘A‘, ‘1‘);
INSERT INTO `a` VALUES (‘x‘, ‘B‘, ‘2‘);
INSERT INTO `a` VALUES (‘x‘, ‘C‘, ‘2‘);
INSERT INTO `a` VALUES (‘x‘, ‘A‘, ‘4‘);
INSERT INTO `a` VALUES (‘y‘, ‘B‘, ‘5‘);
INSERT INTO `a` VALUES (‘y‘, ‘C‘, ‘5‘);
INSERT INTO `a` VALUES (‘y‘, ‘D‘, ‘5‘);
INSERT INTO `a` VALUES (‘z‘, ‘A‘, ‘8‘);
INSERT INTO `a` VALUES (‘z‘, ‘B‘, ‘9‘);
INSERT INTO `a` VALUES (‘x‘, ‘C‘, ‘1‘);
INSERT INTO `a` VALUES (‘x‘, ‘D‘, ‘2‘);
INSERT INTO `a` VALUES (‘y‘, ‘D‘, ‘3‘);
INSERT INTO `a` VALUES (‘y‘, ‘D‘, ‘4‘);
INSERT INTO `a` VALUES (‘z‘, ‘C‘, ‘5‘);
INSERT INTO `a` VALUES (‘z‘, ‘C‘, ‘6‘);
INSERT INTO `a` VALUES (‘z‘, ‘C‘, ‘2‘);
INSERT INTO `a` VALUES (‘z‘, ‘A‘, ‘4‘);

-- 序号、排名
select @rownum:=@rownum+1 xh,a.name,a.val,
if(@lastVal=a.val,@rank,@rank:=@rownum)pm,@lastVal:=a.val
from  a,(select @rownum:=0,@rank:=0,@lastVal:=null) b ORDER BY a.val;
-- 统计为行
select type,name,sum(val) from a GROUP BY a.type,a.name;
-- 统计为行列
select t.type,if(t.name=‘A‘,t.sl,0)A,if(t.name=‘B‘,t.sl,0)B,if(t.name=‘C‘,t.sl,0)C,if(t.name=‘D‘,t.sl,0)D from
(select type,name,sum(val)sl from a GROUP BY a.type,a.name)t;
-- 行转列，方式1
select t1.type,sum(A) sumA,sum(B) sumB,sum(C) sumC,sum(D) sumD from 
(select t.type,if(t.name=‘A‘,t.sl,0)A,if(t.name=‘B‘,t.sl,0)B,if(t.name=‘C‘,t.sl,0)C,if(t.name=‘D‘,t.sl,0)D from
(select type,name,sum(val)sl from a GROUP BY a.type,a.name)t)t1 group by t1.type;
-- 行转列，方式2
select t.type,sum(if(t.name=‘a‘,t.sl,0)) sumA,sum(if(t.name=‘b‘,t.sl,0)) sumB,sum(if(t.name=‘c‘,t.sl,0)) sumC,sum(if(t.name=‘d‘,t.sl,0)) sumD from
(select type,name,sum(val)sl from a GROUP BY a.type,a.name)t group by t.type;