Question

我在使用从另一个表转置的列更新表时遇到问题。我在这里调查并接近解决方案，但我仍然没有达到目的。

我有一个表tbl_g08t1，其中包含以下列以及其他未包含的列（第1行：列名称）：

shl62 carrno    typ stat    50      71      72      73      74      75      76
747  35712528   0   6       29  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)
747  35722615   0   6       29  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)
747  35722625   0   6       29  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)
747  35722664   0   6       29  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)
821  35136730   0   8     (NULL)(NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)
821  35722678   0   8       29  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)
821  35833255   0   6     (NULL)(NULL)  (NULL)  (NULL)  (NULL)  (NULL)  (NULL)

我有第二个表tbl_s80t1，其中包含freetexts，它看起来像：

sysfromt    sysshort freecode freetext
G08T1       35722652    98      101
G08T1       35722652    132     KCF9F27                                                               
G08T1       35722664    50      29
G08T1       35722664    71      20171004
G08T1       35722664    74      01Y                                                                   
G08T1       35722664    75      3
G08T1       35722664    76      A17108176                                                             
G08T1       35722664    97      8397080
G08T1       35722664    98      101
G08T1       35722664    132     KCF9F13                                                               
G08T1       35722678    50      29
G08T1       35722678    71      20171005
G08T1       35722678    74      01Y                                                                   
G08T1       35722678    75      3
G08T1       35722678    76      D1718496                                                              
G08T1       35722678    97      8395896
G08T1       35722678    98      101
G08T1       35722678    132     KCF9F27                                                               
G08T1       35722684    8       2017-10-05 09:53 C:3 Out:9 General fault!                             
G08T1       35722684    8       2017-10-05 09:54 C:3 Out:9 General fault!                             
G08T1       35722684    50      29

我正在尝试将这两个表与

合并

`tbl_g08t1`.`carrno` = `tbl_s80t1`.`sysshort` AND `tbl_s80t1`.`sysfromt` = 'G08T1'

并根据freecode转置第二行的某些行，最后我得到了以下代码：

USE general_db;
    UPDATE tbl_g08t1
    LEFT JOIN `tbl_s80t1` ON (`tbl_g08t1`.`carrno` = `tbl_s80t1`.`sysshort` AND
              `tbl_s80t1`.`sysfromt` = 'G08T1')
      SET
         `50` = (SELECT MAX(`tbl_s80t1`.`freetext`) WHERE `tbl_s80t1`.`freecode` = 50),
         `71` = (SELECT MAX(`tbl_s80t1`.`freetext`) WHERE `tbl_s80t1`.`freecode` = 72),
         `72` = (SELECT MAX(`tbl_s80t1`.`freetext`) WHERE `tbl_s80t1`.`freecode` = 73),
         `76` = (SELECT MAX(`tbl_s80t1`.`freetext`) WHERE `tbl_s80t1`.`freecode` = 76)

问题是只更新了一列50，所有其他71...76都具有所有（NULL）值。我希望那里有freetext个值，当然freecode值是相关的。

好吧，我不知道我是否已经清楚......或者更加困惑...... 谢谢你的提示。

绘

PS 在运行查询时，我收到消息

33278 row(s) affected, 64 warning(s): 1265 Data truncated for column '50' at row 1

Answer 1

问题出在你的set子句中。使用MAX（）和SELECT是一个子查询，并没有引用JOIN子句。他们独立于此。我认为这可能有用：

USE general_db;
UPDATE tbl_g08t1
    SET
     `50` = (SELECT MAX(`tbl_s80t1`.`freetext`) FROM tbl_s80t1 WHERE `tbl_s80t1`.`freecode` = 50 AND `tbl_g08t1`.`carrno` = `tbl_s80t1`.`sysshort` AND `tbl_s80t1`.`sysfromt` = 'G08T1')),
     `71` = (SELECT MAX(`tbl_s80t1`.`freetext`) FROM tbl_s80t1 WHERE `tbl_s80t1`.`freecode` = 71 AND `tbl_g08t1`.`carrno` = `tbl_s80t1`.`sysshort` AND `tbl_s80t1`.`sysfromt` = 'G08T1')),
     `72` = (SELECT MAX(`tbl_s80t1`.`freetext`) FROM tbl_s80t1 WHERE `tbl_s80t1`.`freecode` = 73 AND `tbl_g08t1`.`carrno` = `tbl_s80t1`.`sysshort` AND `tbl_s80t1`.`sysfromt` = 'G08T1')),
     `76` = (SELECT MAX(`tbl_s80t1`.`freetext`) FROM tbl_s80t1 WHERE `tbl_s80t1`.`freecode` = 76 AND `tbl_g08t1`.`carrno` = `tbl_s80t1`.`sysshort` AND `tbl_s80t1`.`sysfromt` = 'G08T1'))

没有SQL小提琴，我无法测试它。

Answer 2

谢谢！有用！我只需要将列50...76的长度从VARCHAR 50更改为255.只有一个额外的＆＃34;）＆＃34;在每个要删除的陈述结束时。执行时间非常好：15秒更新＆gt; 3百万条记录。

MySQL - 更新一个表，其中列从另一个表转换

2 个答案: