在具有奇怪要求的mysql中加入三個表

Question

我的數據庫中有三個表。

Table A具有字段

KEYID | KeyName
27    | Income
28    | Account Number

Table B中的字段

UserID | Email          | Name | Phone
481    | test@gmail.com | test | 99999999

Table C具有字段

ID | KEYID | UserID | Value
1  |   27  |   481  | 10,000

我需要顯示表字段的標題是：

UserID | Email          | Name |   Phone  | Income

並且表值應如下所示：

 481   | test@gmail.com | test | 99999999 | 10,000

我可以獲得應該在表中顯示的KeyID。 在此示例中，KeyIDs字符串為'27'。 我嘗試加入，我可以獲取並在表中顯示值。 但我不知道如何顯示表頭的鍵名。

任何想法。？

Answer 1

您可以使用一對內部聯接

select b.UserID, b.Email , b.Name, c.value as income 
from   tableB as b inner join tableC as C on b.userID = c.userId
inner join tableA as a on a.keyID = c.keyID 
and a.keyname = 'Income';     

以及您在評論中提供的查詢

select 
      b.UserID
    , b.Email 
    , b.Name
    , Group_Concat(Distinct Concat(c.keyID,’^:^’,c.value) 
                          Order By c.id Separator ‘;’) As Keyvalues 
    from tableB as b 
    inner join tableC as C on b.userID = c.userId 
    inner join tableA as a on a.keyID = c.keyID;  

並與CASE應該是

 select 
      b.UserID
    , b.Email 
    , b.Name
    , Group_Concat(Distinct CASE 
            WHEN c.keyID IN ('1,23,10') THEN Concat(c.keyID,’^:^’,c.value) END  
            Order By c.id Separator ‘;’) As Keyvalues 
    from tableB as b 
    inner join tableC as C on b.userID = c.userId 
    inner join tableA as a on a.keyID = c.keyID; 

Answer 2

該查詢應有助於獲得所需的結果。

select b.UserID, b.Email, b.Name, b.Phone, c.Value as Income
from table_b as b
JOIN table_c as c ON (b.UserID = c.UserID)
where c.KEYID = 27

Answer 3

嘗試這個：

SELECT b.userid, b.email, b.name, b.phone, c.value as income
FROM a
LEFT JOIN c on c.keyid = a.keyid
LEFT JOIN b ob b.userid = c.userid