Question

如何转换以下内容以使用INNER JOIN而不是嵌套的SELECT？

SELECT 
    [Name].[NameValueID],
    [Name].[NameTypeID],
    [Name].[NameID],
    [Name].[Value]
FROM [Name] 
WHERE Name.NameTypeID IN ( SELECT NameTypeID FROM @tbNameType ) 
    OR Name.NameID IN ( SELECT NameID FROM @tbName)

Answer 1

这个很棘手，因为它是“OR”条件而不是“AND”。但我认为这样做会：

SELECT 
        [Name].[NameValueID],
        [Name].[NameTypeID],
        [Name].[NameID],
        [Name].[Value]
FROM [Name] 
INNER JOIN  ( SELECT NameTypeID FROM @tbNameType ) t ON t.NameTypeID=Name.NameTypeID

UNION

SELECT 
        [Name].[NameValueID],
        [Name].[NameTypeID],
        [Name].[NameID],
        [Name].[Value]
FROM [Name]
INNER JOIN ( SELECT NameID FROM @tbName) t ON t.NameID = Name.NameID

Answer 2

SELECT DISTINCT
    Name.NameValueID,
    Name.NameTypeID,
    Name.NameID,
    Name.Value
FROM
    Name
    LEFT JOIN @tbNameType a ON a.NameTypeID=Name.NameTypeID
    LEFT JOIN @tbName b ON b.NameID=Name.NameID
WHERE a.NameTypeID IS NOT NULL OR b.NameID IS NOT NULL

将嵌套选择转换为WHERE .. OR ..到INNER JOINS

2 个答案: