完成mysql行轉(zhuǎn)列與列轉(zhuǎn)行的示例代碼分享

mysql行轉(zhuǎn)列、列轉(zhuǎn)行

語(yǔ)句不難，不做多余解釋了，看語(yǔ)句時(shí)，從內(nèi)往外一句一句剖析

行轉(zhuǎn)列

有如圖所示的表，現(xiàn)在希望查詢的結(jié)果將行轉(zhuǎn)成列

建表語(yǔ)句如下：

CREATE TABLE `TEST_TB_GRADE` (
 `ID` int(10) NOT NULL AUTO_INCREMENT,
 `USER_NAME` varchar(20) DEFAULT NULL,
 `COURSE` varchar(20) DEFAULT NULL,
 `SCORE` float DEFAULT '0',
 PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

insert into TEST_TB_GRADE(USER_NAME, COURSE, SCORE) values
("張三", "數(shù)學(xué)", 34),
("張三", "語(yǔ)文", 58),
("張三", "英語(yǔ)", 58),
("李四", "數(shù)學(xué)", 45),
("李四", "語(yǔ)文", 87),
("李四", "英語(yǔ)", 45),
("王五", "數(shù)學(xué)", 76),
("王五", "語(yǔ)文", 34),
("王五", "英語(yǔ)", 89);

查詢語(yǔ)句：

此處用之所以用MAX是為了將無(wú)數(shù)據(jù)的點(diǎn)設(shè)為0，防止出現(xiàn)NULL

SELECT user_name ,
  MAX(CASE course WHEN '數(shù)學(xué)' THEN score ELSE 0 END ) 數(shù)學(xué),
  MAX(CASE course WHEN '語(yǔ)文' THEN score ELSE 0 END ) 語(yǔ)文,
  MAX(CASE course WHEN '英語(yǔ)' THEN score ELSE 0 END ) 英語(yǔ)
FROM test_tb_grade
GROUP BY USER_NAME;

結(jié)果展示：

列轉(zhuǎn)行

有如圖所示的表，現(xiàn)在希望查詢的結(jié)果將列成行

建表語(yǔ)句如下：

CREATE TABLE `TEST_TB_GRADE2` (
 `ID` int(10) NOT NULL AUTO_INCREMENT,
 `USER_NAME` varchar(20) DEFAULT NULL,
 `CN_SCORE` float DEFAULT NULL,
 `MATH_SCORE` float DEFAULT NULL,
 `EN_SCORE` float DEFAULT '0',
 PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

insert into TEST_TB_GRADE2(USER_NAME, CN_SCORE, MATH_SCORE, EN_SCORE) values
("張三", 34, 58, 58),
("李四", 45, 87, 45),
("王五", 76, 34, 89);

查詢語(yǔ)句：

select user_name, '語(yǔ)文' COURSE , CN_SCORE as SCORE from test_tb_grade2
union select user_name, '數(shù)學(xué)' COURSE, MATH_SCORE as SCORE from test_tb_grade2
union select user_name, '英語(yǔ)' COURSE, EN_SCORE as SCORE from test_tb_grade2
order by user_name,COURSE;

結(jié)果展示：

以上就是實(shí)現(xiàn)mysql行轉(zhuǎn)列和列轉(zhuǎn)行的示例代碼分享的詳細(xì)內(nèi)容，更多請(qǐng)關(guān)注php中文網(wǎng)其它相關(guān)文章！