Question

我有2个表，由查询说明：

CT_Validation

select ValidationID, Message from CT_Validation

ValidationID    Message
======================================================
IP_Validator    Not a valid IP address
NumbersOnly     Invalid number.
SSN             Not a valid social security number.
10Digits        A 10-digit number is required.

CT_Validation_Lang

select ValidationID, LangID, Message from CT_Validation_Lang

ValidationID  LangID  Message
======================================================
SSN           es      Peligro es mi segundo nombre!

如何建立联接，以便LangID = 'es'我会回来：

ValidationID    Message
======================================================
IP_Validator    Not a valid IP address
NumbersOnly     Invalid number.
SSN             Peligro es mi segundo nombre!
10Digits        A 10-digit number is required.

...但如果LangID为空，空或除“es”以外的任何内容，则结果将恢复为所有英语：

ValidationID    Message
======================================================
IP_Validator    Not a valid IP address
NumbersOnly     Invalid number.
SSN             Not a valid social security number.
10Digits        A 10-digit number is required.

重要提示：关键字段为ValidationID，此示例中的重要键值为SSN，因为它存在于两个表中。

提前感谢任何建议。

Answer 1

我认为你想要left join和coalesce

select cv.ValidationID, coalesce(cvl.Message, cv.Message) 
from CT_Validation cv
left join CT_Validation_Lang cvl on cv.ValidationID = cvl.ValidationID
     and cvl.LangID = 'es'

如果Message CT_Validation_Lang存在LangID，则会从es中选择Message。否则它将从CT_Validation

返回

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  let res;
  try {
    res = await Bundle.sdk.find(slug);
  } catch (err) {
    console.log('Fragment didn\'t work ========', slug, err);

    try {
      res = await Bundle.sdk.find(`package/${slug}`);
    } catch (e) {
      console.log('Fragment didn\'t work package ========', e);

      try {
        res = await Bundle.sdk.find(`${slug}-list`);
      } catch (error) {
        console.log('None of the fragments worked================.', error);
      }
    }
  }

  return logResponse(res);
};

identityCheck('fashion');

Answer 2

使用CASE

的一种方法

SELECT
  ctv.ValidationID,
  CASE WHEN ctvl.LangID = 'es' THEN ctvl.message ELSE ctv.message END AS Message
FROM CT_Validation ctv
LEFT JOIN CT_Validation_Lang ctvl ON ctv.ValidationId = ctvl.ValidationId
  AND ctvl.LangID = 'es'

Answer 3

你可以这样做：

select v.ValidationID, coalesce(vl.message, v.message) as message
from CT_Validation v left join
     CT_Validation_Lang vl
     ON vl.ValidationID = v.ValidationID and vl.LangID = 'es';

当西班牙语翻译可用时，这将从CT_Validation_Lang中选择消息。否则，它会选择原始消息。

Answer 4

类似的东西： -

select 
  ctv.ValidationID, 
  coalesce(
          (select 
             ctvl.Message 
           from 
             CT_Validation_Lang ctvl 
           where 
             ctvl.ValidationID = ctv.ValidationID and 
             LangID = 'es'
           ), 
           ctv.Message, ' ') as Message 
  from 
    CT_Validation ctv;

Answer 5

将ISNULL()功能与left join一起使用。

select a.ValidationID, ISNULL(b.message, a.message) 
from CT_Validation a
left join CT_Validation_Lang b on a.ValidationID = b.ValidationID and b.LangID = 'es'

如何根据记录存在从2个表中选择1条记录？

5 个答案: