如何解决使用数据透视表连接使用 Mysql 8 版本的表
我有这两个表 t1 和 t2 存储了一个数据库 MysqL 版本 8.0.17
需要说明的是，表 t2 可以包含数千行不同的单元代码（字段 sUn）...
相反，表 t1 仅包含每个单元的方式和代码（字段 TABLE_NAME）
-- ----------------------------
-- Table structure for t1
-- ----------------------------
DROP TABLE IF EXISTS `t1`;
CREATE TABLE `t1` (
`TABLE_NAME` varchar(255) DEFAULT NULL,`tDDMMYYHHMMSS` datetime DEFAULT NULL,`sID` int(11) NOT NULL AUTO_INCREMENT,PRIMARY KEY (`sID`) USING BTREE,UNIQUE INDEX `TABLE_NAME`(`TABLE_NAME`) USING BTREE
) ENGINE = InnoDB;
-- ----------------------------
-- Records of t1
-- ----------------------------
INSERT INTO `t1` VALUES ('100','2021-04-09 12:44:30',1);
INSERT INTO `t1` VALUES ('11c',2);
INSERT INTO `t1` VALUES ('11f',3);
INSERT INTO `t1` VALUES ('12a',4);
INSERT INTO `t1` VALUES ('12h',5);
-- ----------------------------
-- Table structure for t2
-- ----------------------------
DROP TABLE IF EXISTS `t2`;
CREATE TABLE `t2` (
`sid` int(11) NOT NULL AUTO_INCREMENT,`sUn` varchar(255) DEFAULT NULL,`sUnName` varchar(255) DEFAULT NULL,`sContents` longtext NULL,PRIMARY KEY (`sid`) USING BTREE
) ENGINE = InnoDB;
-- ----------------------------
-- Records of t2
-- ----------------------------
INSERT INTO `t2` VALUES (1,'100','nor','Ipsa sua melior fama.');
INSERT INTO `t2` VALUES (2,'In toto.');
INSERT INTO `t2` VALUES (3,'Homines,nihil agendo.');
INSERT INTO `t2` VALUES (4,'11C','SAR','Habere non haberi.');
INSERT INTO `t2` VALUES (5,'Vivere est cogitare.');
INSERT INTO `t2` VALUES (6,'Urbi et Orbi.');
INSERT INTO `t2` VALUES (7,'11F','SAD','Inter sidera versor.');
INSERT INTO `t2` VALUES (8,'Una tantum.');
INSERT INTO `t2` VALUES (9,'Carthago delenda est.');
INSERT INTO `t2` VALUES (10,'12A','RIV','Status quo.');
INSERT INTO `t2` VALUES (11,'Aut aut.');
INSERT INTO `t2` VALUES (12,'Condicio sine qua non.\r\n');
INSERT INTO `t2` VALUES (13,'12H','CUN','Ubi maior minor cessat.');
INSERT INTO `t2` VALUES (14,'Carpe diem.');
INSERT INTO `t2` VALUES (15,'venni,vidi,vinsi.');
我已经尝试过 -没有成功- 一个查询数据透视表将这两个表连接起来以获得此返回
+------------------------+----------------------+-----------------------+------------------------+-------------------------+
| nor | SAR | SAD | RIV | CUN |
+------------------------+----------------------+-----------------------+------------------------+-------------------------+
| Ipsa sua melior fama. | Habere non haberi. | Inter sidera versor. | Status quo. | Ubi maior minor cessat. |
| In toto. | Vivere est cogitare. | Una tantum. | Aut aut. | Carpe diem. |
| Homines,nihil agendo. | Urbi et Orbi. | Carthago delenda est. | Condicio sine qua non. | venni,vinsi. |
+------------------------+----------------------+-----------------------+------------------------+-------------------------+
任何帮助将不胜感激...谢谢。
SELECT
max(
IF
( t.sUn = q.TABLE_NAME,t.sContents,NULL )) q.sUnName
FROM
( SELECT row_number() over ( PARTITION BY sUn ORDER BY sID ) AS rn,tcs.sUn,tcs.sContents FROM t2 AS tcs ) AS t
JOIN t1 q ON t.sUn = q.TABLE_NAME
GROUP BY
rn
ORDER BY
rn
1064 - 您的 sql 语法有错误；检查与您的 MysqL 服务器版本相对应的手册，了解在 '.sUnName 附近使用的正确语法 从 ( SELECT row_number() over ( PARTITION BY sUn ORDER BY sID ) AS' 在第 4 行 > 时间：0,001s
更新
使用存储过程的新版本...
CREATE DEFINER=`root`@`localhost` PROCEDURE `pivot_20210409`()
BEGIN
SET SESSION group_concat_max_len = 1000000;
SELECT
CONCAT('SELECT ',GROUP_CONCAT(
CONCAT (
"IF(`sUnName` = '",sUnName,'\',sContents,NULL) AS `','`'
)
),' FROM `t2`'
) INTO @sql
FROM
( SELECT row_number() over ( PARTITION BY sUn ORDER BY sID ) AS rn,tcs.sUnName,tcs.sContents FROM t2 AS tcs
GROUP BY tcs.sUnName
) AS data;
SELECT @sql;
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END
返回
+------------------------+----------------------+-----------------------+--------------------------+-------------------------+
| nor | SAR | SAD | RIV | CUN |
+------------------------+----------------------+-----------------------+--------------------------+-------------------------+
| Ipsa sua melior fama. | NULL | NULL | NULL | NULL |
| In toto. | NULL | NULL | NULL | NULL |
| Homines,nihil agendo. | NULL | NULL | NULL | NULL |
| NULL | Habere non haberi. | NULL | NULL | NULL |
| NULL | Vivere est cogitare. | NULL | NULL | NULL |
| NULL | Urbi et Orbi. | NULL | NULL | NULL |
| NULL | NULL | Inter sidera versor. | NULL | NULL |
| NULL | NULL | Una tantum. | NULL | NULL |
| NULL | NULL | Carthago delenda est. | NULL | NULL |
| NULL | NULL | NULL | Status quo. | NULL |
| NULL | NULL | NULL | Aut aut. | NULL |
| NULL | NULL | NULL | Condicio sine qua non. | NULL |
| NULL | NULL | NULL | NULL | Ubi maior minor cessat. |
| NULL | NULL | NULL | NULL | Carpe diem. |
| NULL | NULL | NULL | NULL | venni,vinsi. |
+------------------------+----------------------+-----------------------+--------------------------+-------------------------+
解决方法
在的MySQL，伤心的说，转动是困难的任意命名的列的乱七八糟的事情。
这会得到您想要的结果（db-fiddle.com 上的 dbfiddle，它提供 MySQL 8。）
WITH pivot AS (
SELECT CASE WHEN SunName = 'NOR' THEN sContents ELSE NULL END NOR,CASE WHEN SunName = 'SAR' THEN sContents ELSE NULL END SAR,CASE WHEN SunName = 'SAD' THEN sContents ELSE NULL END SAD,CASE WHEN SunName = 'RIV' THEN sContents ELSE NULL END RIV,CASE WHEN SunName = 'CUN' THEN sContents ELSE NULL END CUN,sId
FROM t2
),rownums AS (
SELECT sId,row_number() OVER ( PARTITION BY sUn ORDER BY sID ) rn FROM t2
)
SELECT MAX(NOR) NOR,MAX(SAR) SAR,MAX(SAD) SAD,MAX(RIV) RIV,MAX(CUN) CUN
FROM rownums
JOIN pivot ON rownums.sId = pivot.sId
GROUP BY rownums.rn
这个讨厌的子查询执行旋转操作。 (fiddle) 看看它是如何枚举列的？这几乎就是你必须做的
SELECT CASE WHEN SunName = 'NOR' THEN sContents ELSE NULL END NOR,sId
FROM t2
您可以编写一个使用字符串处理和 MySQL's PREPARE statement 来合成此类查询的存储过程。这是一项相当大的工作。 Advice here。
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