Question

我需要ActPartB表上的ParteB字段的所有唯一值与userActTable匹配相同的IDNumber但仅适用于某些userIDNumber的条件（在userActTable上）

带有“WHERE”的完整sql字符串

sql = "SELECT DISTINCT ParteB FROM ActParteB INNER JOIN userAct ON IDNumber = IDNumber WHERE userAct.userIDNumber = ? order by ParteB asc"

然后我添加

cmdConnection.Parameters.AddWithValue("@userIDNumber", NumberOfActiveuser)

程序运行时没有调试错误，但它显示了ActPartB的所有唯一字段，无论userIDNumber的值如何。 os userIDNumber值很好，因为。

只是WHERE被“忽略”

此

sql = "SELECT DISTINCT ParteB FROM ActParteB INNER JOIN userAct ON IDNumber = IDNumber WHERE userAct.userIDNumber = ? order by ParteB asc"

产生与此相同的输出

sql = "SELECT DISTINCT ParteB FROM ActParteB INNER JOIN userAct ON IDNumber = IDNumber order by ParteB asc"

Where子句有什么问题？

完整代码：

Using conn As New SQLiteConnection(SQLiteConnStr)

Try
    conn.Open()

    Dim cmdConnection As SQLiteCommand = New SQLiteCommand(sql, conn)

    Dim sql = "SELECT DISTINCT ParteB FROM ActParteB INNER JOIN userAct ON IDNumber = IDNumber WHERE userAct.userIDNumber = ? order by ParteB asc"

            cmdConnection.Parameters.AddWithValue("@userIDNumber", NumberOfActiveUser)

            Dim readerParteB As SQLiteDataReader = cmdConnection.ExecuteReader()

            ParteBComboBox.Items.Clear()

            Try
                While (readerParteB.Read())
                    ParteBComboBox.Items.Add(readerParteB("ParteB"))
                End While
            Catch ex As Exception
                MsgBox(ex.ToString())
            End Try

            Catch ex As Exception
                MsgBox(ex.ToString())
            End Try

End Using

Answer 1

Dim cmdConnection As SQLiteCommand = New SQLiteCommand(sql, conn)

Dim sql = "..."

您的命令无法正常运行，因为它使用了不同的SQL字符串（您在代码的某些部分中声明的其他sql变量的值）。

此外，正如Jinx88909所述，您必须将表名添加到联接中以指定您所指的IDNumber列（如果有疑问，数据库当然会选择错误的列）：

... JOIN userAct ON userAct.IDNumber = ActParteB.IDNumber ...
                    ^^^^^^^^           ^^^^^^^^^^

或者，当列名相同时，最好使用USING，它会自动从两个表中获取列：

... JOIN userAct USING (IDNumber) ...

Where子句不处理SQLite Join请求

1 个答案: