主题：[求助]怎么在SQL中表达集合或数组？

Dim myDt As DataTable
Dim myDtCmd As New SqlCommand
Dim myStringSql As String
Dim myList As New List(of String)
myList.add("a")
myList.add("b")
mystringSql = "s-elect * from {表A} where 第四列 in  mylist"
myDtCMd.commandText = myStringSql
myDT = myDtcMd.ExecuteReader()

output.show(myDt.datarows.count)

在mystringSql中，in mylist 该如何正确表达？