标题：请问上述代码错哪儿了？

for each dc1 As datacol in datatables("Zstb").datacols
    for each dc As datacol in datatables("Zszy").datacols
        if dc1.name = dc.name then
            Exit For
        elseif  dc1.name <> dc.name then
            Dim Len As Integer = DataTables("Zszy").DataCols(dc.name).MaxLength
            DataTables("Zstb").DataCols.Add(dc.name, GetType(string),len)
        end if
    next
next
上述代码是两个表中如果zstb表中无zszy表中的列就增加列，有就退出，无就增加，请问上述代码错哪儿了？

for each dc1 As datacol in datatables("Zstb").datacols
    for each dc As datacol in datatables("Zszy").datacols
        if dc1.name = dc.name then
            Exit For
        else
            Dim Len As Integer = DataTables("Zszy").DataCols(dc.name).MaxLength
            DataTables("Zstb").DataCols.Add(dc.name, GetType(string),len)
        end if
    next
next


晕，让楼主带沟里去了！

已改正
for each dc1 As datacol in datatables("Zstb").datacols
    for each dc As datacol in datatables("Zszy").datacols
        If DataTables("Zstb").DataCols.Contains(dc.name) Then
            exit for
        else
            Dim Len As Integer = DataTables("Zszy").DataCols(dc.name).MaxLength
            DataTables("Zstb").DataCols.Add(dc.name, GetType(string),len)
        end if
    next
next

for each dc1 As datacol in datatables("Zstb").datacols     for each dc As datacol in datatables("Zszy").datacols         if dc1.name = dc.name then             'Exit For  这个不要了,否则遍历完之前一旦有相同的列,就停止执行了~         elseif  dc1.name <> dc.name then             Dim Len As Integer = DataTables("Zszy").DataCols(dc.name).MaxLength             DataTables("Zstb").DataCols.Add(dc.name, GetType(string),len)         end if     next next 或者这样: for each dc1 As datacol in datatables("Zstb").datacols     for each dc As datacol in datatables("Zszy").datacols         iif  dc1.name <> dc.name then             Dim Len As Integer = DataTables("Zszy").DataCols(dc.name).MaxLength             DataTables("Zstb").DataCols.Add(dc.name, GetType(string),len)         else             return         end if     next next