MySQL 动态行转列
`id` INT(11) DEFAULT NULL,
`kemu` VARCHAR(20) COLLATE utf8_unicode_ci DEFAULT NULL
) ENGINE=INNODB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
INSERT INTO tbl01(id, kemu) VALUES ('1', '语文');
INSERT INTO tbl01(id, kemu) VALUES ('2', '数学');
INSERT INTO tbl01(id, kemu) VALUES ('3', '英语');
INSERT INTO tbl01(id, kemu) VALUES ('4', '物理');
INSERT INTO tbl01(id, kemu) VALUES ('5', '化学');
CREATE TABLE `tbl02` (
`nid` VARCHAR(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`kemu` VARCHAR(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`chji` INT(11) DEFAULT NULL
) ENGINE=INNODB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
INSERT INTO tbl02 (nid, kemu, chji) VALUES ('李明', '1', '95');
INSERT INTO tbl02 (nid, kemu, chji) VALUES ('李明', '2', '89');
INSERT INTO tbl02 (nid, kemu, chji) VALUES ('李明', '4', '74');
INSERT INTO tbl02 (nid, kemu, chji) VALUES ('张三', '1', '81');
INSERT INTO tbl02 (nid, kemu, chji) VALUES ('张三', '3', '65');
INSERT INTO tbl02 (nid, kemu, chji) VALUES ('张三', '5', '38');
SET @sql := 'SELECT nid';
SELECT @sql := CONCAT(@sql, ', max(case kemu when ', id, ' then chji else 0 end) as ', kemu)
FROM (SELECT DISTINCT id, kemu FROM tbl01) AS a;
SELECT @sqlstr := CONCAT(@sql, ' from tbl02 group by nid');
PREPARE rc FROM @sqlstr;
EXECUTE rc;
CREATE
TABLE
`tbl03` (
`id`
int
(11)
DEFAULT
NULL
,
`xm`
varchar
(20)
COLLATE
utf8_unicode_ci
DEFAULT
NULL
,
`nj`
int
(11)
DEFAULT
NULL
,
`km`
varchar
(20)
COLLATE
utf8_unicode_ci
DEFAULT
NULL
,
`cj`
int
(11)
DEFAULT
NULL
) ENGINE=InnoDB
DEFAULT
CHARSET=utf8
COLLATE
=utf8_unicode_ci
统计每个人各年级的总成绩：
SET @sql := 'SELECT xm';
SELECT @sql := CONCAT(@sql, ', sum(case nj when ', nj, ' then cj else 0 end) as `', nj, '年级`')
FROM (SELECT nj FROM tbl03 GROUP BY nj) AS a;
SELECT @sqlstr := CONCAT(@sql, ' from tbl03 group by xm');
PREPARE rc FROM @sqlstr;
EXECUTE rc;