Question

是否可以通过连接另一个表中的列数据来更新一个表列数据？让我用简单的例子来解释，

表A：studentaccess

╔════════╦══════════╗
║ UserID ║ AccCode  ║
╠════════╬══════════╣
║    12  ║ Tom      ║
║    13  ║ Ann      ║
╚════════╩══════════╝

表B：studentdetails

╔════════╦═══════════════════╗
║ ID     ║ UserName          ║
╠════════╬═══════════════════╣
║    1   ║ raj_12_kumar      ║
║    2   ║ test_13_test      ║
╚════════╩═══════════════════╝

现在我要拆分UserName列数据并从中查取第二个令牌，并通过匹配studentaccess查询UserID表并从中获取AccCode值并将其与UserName列数据的第二个标记连接起来。最后，我需要studentdetails表数据，如下所示，

╔════════╦═══════════════════╗
║ ID     ║ UserName          ║
╠════════╬═══════════════════╣
║    1   ║ 12_Tom            ║
║    2   ║ 13_Ann            ║
╚════════╩═══════════════════╝

从下面的substr查询中，我可以从UserId表中的UserName列获取studentdetails值，

select regexp_substr(UserName, '([^_]+)(_[^_]+){1}$', 1, 1, null, 1) as userId  from studentdetails

任何人都可以帮助我与Acccode连接相同内容并在UserName列中更新相同内容吗？

Answer 1

UPDATE StudentDetails sd
SET UserName = 
( 
    SELECT userid||'_'||AccCode 
    FROM StudentAccess sa 
    WHERE regexp_substr(sd.UserName, '([^_]+)(_[^_]+){1}$', 1, 1, null, 1) = sa.userid
);

Answer 2

您可以使用以下查询，我已经在我的测试和验证。

您可以在此sqlfiddle查看Oracle版本：http://sqlfiddle.com/#!4/cd66c/1

Oracle版

UPDATE studentdetails sd
SET sd.UserName =
  (SELECT  to_char(x.UserID) || '_' || sa.AccCode
   FROM 
     (SELECT  sd1.ID as ID, SUBSTR(sd1.UserName, INSTR( sd1.UserName,'_') + 1, INSTR( sd1.UserName,'_', INSTR( sd1.UserName,'_') + 1) - 1 - INSTR( sd1.UserName,'_')) AS UserID
      FROM studentdetails sd1 
     ) x  INNER JOIN studentaccess sa ON TO_NUMBER(x.UserID) = sa.UserID where sd.ID = x.ID   
  );

SQL Server版本

UPDATE studentdetails
SET UserName =
  (SELECT x.UserID + '_' + sa.AccCode
   FROM
     (SELECT SUBSTRING(sd1.UserName, CHARINDEX('_', sd1.UserName) + 1, CHARINDEX('_', sd1.UserName, CHARINDEX('_', sd1.UserName) + 1) - 1 - CHARINDEX('_', sd1.UserName)) AS UserID
      FROM studentdetails sd1
      WHERE sd1.ID = studentdetails.ID) x
   INNER JOIN studentaccess sa ON x.UserID = sa.UserID);

更新1

如果studentaccess表中不包含从studentdetails表中获取的UserID，则可以在studentdetails表的UserName列中使用字符串UNKNOWN来使用下面的查询。

我无法在sqlfiddle中尝试，因为由于某些问题，sqlfiddle没有加载。无论什么时候，它都会重新上线，我会尝试一下让你知道。在此期间，您可以尝试这一点，让我知道任何问题。

UPDATE studentdetails sd
SET sd.UserName =
  (SELECT  CASE when x.ID is null then 'UNKNOWN' else  to_char(x.UserID) || '_' || sa.AccCode END
   FROM 
     (SELECT  sd1.ID as ID, SUBSTR(sd1.UserName, INSTR( sd1.UserName,'_') + 1, INSTR( sd1.UserName,'_', INSTR( sd1.UserName,'_') + 1) - 1 - INSTR( sd1.UserName,'_')) AS UserID
      FROM studentdetails sd1 
     ) x  RRIGHT OUTER JOIN studentaccess sa ON TO_NUMBER(x.UserID) = sa.UserID where sd.ID = x.ID   
  );

Answer 3

你差不多了。您可以使用userName连接其他列。

regexp_substr(UserName, '([^_]+)(_[^_]+){1}$', 1, 1, null, 1) || '_' || acccode

您的样本数据的结果将是这样的 -

    select userid, regexp_substr(UserName, '([^_]+)(_[^_]+){1}$', 1, 1, null, 1) || '_' || acccode as username  from 
(
select 1 UserID, 'Tom' AccCode from dual
union
select  1 userid , 'Ann' AccCode from dual) studentaccess,
( select 1 ID, 'raj_12_kumar' username from dual
 union
 select 2 id, 'test_13_test' username from dual) studentdetails
 where studentaccess.userid = studentdetails.ID

将列与两个表连接在一起

3 个答案: