查询中的 SQL 查询答案

【问题标题】：SQL query in a query查询中的 SQL 查询
【发布时间】：2013-05-30 16:00:23
【问题描述】：

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我的数据库中有这种结构。我需要建立一个员工姓名列表，然后是他们的部门和办公室的名称。到目前为止，我已经来到了这个查询：

ALTER PROCEDURE FilterEmpList
    @empName nvarchar(250) = null,
    @empDepID int = null,
    @empOfficeID int = null,
    @empPosID int = null    
AS 
BEGIN
SELECT 
    E.emp_id AS 'emp_id',
    E.emp_name AS 'emp_name',      
    (SELECT pos_name FROM Positions WHERE pos_id=EP.pos_id) AS 'pos_name',
    (SELECT dep_name FROM Departments WHERE dep_id=OS.dep_id) AS 'dep_name',
    (SELECT office_name FROM Offices WHERE office_id=OS.office_id) AS 'office_name'
FROM 
    Org_Structure OS INNER JOIN (Emp_Positions EP INNER JOIN Employees E ON EP.emp_id=E.emp_id) ON OS.chain_id=EP.chain_id      
WHERE 
    (E.emp_name LIKE '%'+@empName+'%' OR @empName IS NULL)
    AND
    (OS.dep_id = @empDepID OR @empDepID IS NULL)
    AND
    (OS.office_id = @empOfficeID OR @empOfficeID IS NULL)
    AND
    (EP.pos_id = @empPosID OR @empPosID IS NULL)
END

当我以这种方式执行 exec FilterEmpList 时，出现错误：Invalid object name 'EP'。

【问题讨论】：

标签： sql-server tsql inner-join invalid-object-name

【解决方案1】：

您不能在其范围之外引用内联选择表。我建议使用自然连接，例如：

Select Emp_ID,Emp_Name,Dep_Name,Office_Name,Pos_Name
From Employees e
Join Emp_positions ep on ep.Emp_ID = e.Emp_ID
Join Org_Structue os on os.Chain_ID = ep.Chain_ID
Join Departments d on d.Dep_ID = os.Dep_ID
Join Offices o on o.office_ID = os.Office_ID
Join Positions p on p.Pos_ID = os.Pos_ID
Where (E.emp_name LIKE '%'+@empName+'%' OR @empName IS NULL)
    AND
    (OS.dep_id = @empDepID OR @empDepID IS NULL)
    AND
    (OS.office_id = @empOfficeID OR @empOfficeID IS NULL)
    AND
    (EP.pos_id = @empPosID OR @empPosID IS NULL)

【讨论】：

【解决方案2】：

您的内部联接/联接存在问题。在看到查询和 ERD 之后，我假设您正在寻找这个，

ALTER PROCEDURE FilterEmpList
    @empName nvarchar(250) = null,
    @empDepID int = null,
    @empOfficeID int = null,
    @empPosID int = null    
AS 
BEGIN
SELECT 
    E.emp_id AS 'emp_id',
    E.emp_name AS 'emp_name',      
    (SELECT pos_name FROM Positions WHERE pos_id=EP.pos_id) AS 'pos_name',
    (SELECT dep_name FROM Departments WHERE dep_id=OS.dep_id) AS 'dep_name',
    (SELECT office_name FROM Offices WHERE office_id=OS.office_id) AS 'office_name'
FROM 
    Org_Structure OS 
INNER JOIN Emp_Positions EP ON EP.ChainId ==  Emp_Positions.ChainId
INNER JOIN Employees E ON EP.emp_id=E.emp_id      
WHERE 
    (E.emp_name LIKE '%'+@empName+'%' OR @empName IS NULL)
    AND
    (OS.dep_id = @empDepID OR @empDepID IS NULL)
    AND
    (OS.office_id = @empOfficeID OR @empOfficeID IS NULL)
    AND
    (EP.pos_id = @empPosID OR @empPosID IS NULL)
END

同时尝试使别名更易读。

谢谢

【讨论】：

【解决方案3】：

这可能对你有帮助 -

ALTER PROCEDURE dbo.FilterEmpList
    @empName nvarchar(250) = null,
    @empDepID int = null,
    @empOfficeID int = null,
    @empPosID int = null    
AS 
BEGIN

    SELECT 
        E.emp_id,
        E.emp_name,      
        p.pos_name,
        d.dep_name,
        o.office_name
    FROM dbo.Org_Structure OS 
    JOIN dbo.Emp_Positions EP ON OS.chain_id=EP.chain_id  
    /*LEFT*/ JOIN dbo.Employees E ON EP.emp_id=E.emp_id 
    /*LEFT*/ JOIN dbo.Positions p ON p.pos_id=EP.pos_id
    /*LEFT*/ JOIN dbo.Departments d ON d.dep_id=OS.dep_id
    JOIN dbo.Offices o ON o.office_id=OS.office_id  
    WHERE (
              E.emp_name LIKE '%'+@empName+'%' 
            OR 
              @empName IS NULL
        )
        AND OS.dep_id = ISNULL(@empDepID, OS.dep_id)
        AND OS.office_id = ISNULL(@empOfficeID, OS.office_id)
        AND EP.pos_id = ISNULL(@empPosID, EP.pos_id)

END

【讨论】：

【解决方案4】：

您的查询将失败，因为您尝试将 EP 加入 Org_structure 表，但此 EP 在括号内。这是不允许的。试试下面

ALTER PROCEDURE FilterEmpList
@empName nvarchar(250) = null,
@empDepID int = null,
@empOfficeID int = null,
@empPosID int = null    
 AS 
  BEGIN
 SELECT 
 E.emp_id AS 'emp_id',
 E.emp_name AS 'emp_name',      
(SELECT pos_name FROM Positions WHERE pos_id=EP.pos_id) AS 'pos_name',
(SELECT dep_name FROM Departments WHERE dep_id=OS.dep_id) AS 'dep_name',
(SELECT office_name FROM Offices WHERE office_id=OS.office_id) AS 'office_name'
FROM 
  Org_Structure OS 
  INNER JOIN Emp_Positions EP ON OS.chain_id=EP.chain_id 
  INNER JOIN Employees E ON EP.emp_id=E.emp_id     
WHERE 
 (E.emp_name LIKE '%'+@empName+'%' OR @empName IS NULL)
AND
 (OS.dep_id = @empDepID OR @empDepID IS NULL)
AND
 (OS.office_id = @empOfficeID OR @empOfficeID IS NULL)
AND
 (EP.pos_id = @empPosID OR @empPosID IS NULL)
END

【讨论】：

【解决方案5】：

您好，您检查过您的表 EMP_Positions 是否存在？

【讨论】：

【解决方案6】：

我认为你们中的一些代码放错了位置。试试这个...

SELECT 
    E.emp_id AS 'emp_id',
    E.emp_name AS 'emp_name',      
    P.pos_name  AS 'pos_name',
    D.dep_name AS 'dep_name',
    O.office_name AS 'office_name'
FROM 
    Org_Structure OS 
    INNER JOIN Emp_Positions EP ON OS.chain_id=EP.chain_id 
    INNER JOIN Employees E ON EP.emp_id=E.emp_id    
    LEFT JOIN Positions P ON P.pos_id=EP.pos_id
    LEFT JOIN Departments D ON D.dep_id=OS.dep_id
    LEFT JOIN Offices O ON O.office_id=OS.office_id
WHERE 
    (E.emp_name LIKE '%'+@empName+'%' OR @empName IS NULL)
    AND
    (OS.dep_id = @empDepID OR @empDepID IS NULL)
    AND
    (COALESCE(O.office_id,@empOfficeID ) = @empOfficeID OR @empOfficeID IS NULL)
    AND
    (EP.pos_id = @empPosID OR @empPosID IS NULL)

【讨论】：

@Vladimir 我已将子查询移出 SELECT，因为其中 oen 中对 EP 的引用可能是问题
@Vladimir 我修改以展示如何使用合并来保留 NULL - 您可能希望在 SELECT 中添加进一步的合并以放置“无办公室”或缺失的内容，具体取决于你想要达到的目标
@Devart 的 ISNULL 子句比我的更干净——我推荐那些
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