主题：查询数据

想从好几个表中查询是否有某一个数据，怎么写代码简洁一些？

Dim ts() As String = {"表A", "表B", "表C"}
For Each t As String In ts
    Dim fdr As DataRow = DataTables(t).Find("")
    If fdr IsNot Nothing Then
       
    End If
Next

这样还是得在代码中输入列名。

Dim ts() As String = {"表A", "表B", "表C"}
For Each t As String In ts
    Dim dt As DataTable = DataTables(t)
    For Each dc As DataCol In dt.datacols
        Dim fdr As DataRow = dt.Find("convert(" & dc.name & ",'System.String') = '" & 123 & "'")
        If fdr IsNot Nothing Then
            msgbox(3)
        End If
    Next
Next

Dim ts() As String = {"表A", "表B", "表C"}
For Each t As String In ts
    Dim dt As DataTable = DataTables(t)
    For Each dc As DataCol In dt.datacols
        Dim fdr As DataRow = dt.sqlFind("convert(" & dc.name & ",'System.String') = '" & 123 & "'")
        If fdr IsNot Nothing Then
            msgbox(3)
        End If
    Next
Next

多表、多列，尽量不要用sqlFind，不然多次使用sqlFind，效率很慢的。

 

Dim ts() As String = {"表A", "表B", "表C"}
For Each t As String In ts
    Dim dt As DataTable = DataTables(t)
    For Each dc As DataCol In dt.datacols
        If dc.IsString Then
            Dim fdr As DataRow = dt.sqlFind(dc.name & " = '" & 123 & "'")
            If fdr IsNot Nothing Then
                msgbox(3)
            End If
        End If
    Next
Next

找到数据后，想要只加载找到的行（数据源为外部数据源），应该如何写代码？

Dim ts() As String = {"表A", "表B", "表C"}
For Each t As String In ts
    Dim dt As DataTable = DataTables(t)
    Dim idxs As String = "-1,"
    For Each dc As DataCol In dt.datacols
        If dc.IsString Then
            Dim fdr As DataRow = dt.sqlFind(dc.name & " = '" & 123 & "'")
            If fdr IsNot Nothing Then
                idxs = idxs & fdr("_Identify") & ","
                Exit For
            End If
        End If
    Next
    dt.LoadFilter = "[_Identify] in (" & idxs.trim(",") & ")"
    dt.load
Next

好的，谢谢

sqlFind只能查找到符合的一条数据，有时候符合的数据比较多，需要在查找到后，并将符合数据加载，应该怎么写呢？