如何在两张表中搜索？

Question

我只想在一个textbox中搜索，如果搜索到的id在学生或教师表中都是相同的，它将查看表格并显示数据，但我不知道如何。

cn.Open() 

    With cmd 
     .Connection = cn 
     If (dt.Rows.Count > 0) Then 
      .CommandText = "SELECT * FROM Students WHERE Familyname = '" & search.Text & "' OR Firstname = '" & search.Text & "' OR StudentID = '" & search.Text & "' OR RFID = '" & search.Text & "'" 
      Searchfrm.Show() 
      da.SelectCommand = cmd 
      dt.Clear() 
      da.Fill(dt) 
      cn.Close() 

     Else : .CommandText = "SELECT * FROM FactandStaff WHERE Familyname LIKE '%" & search.Text & "%' OR Firstname LIKE '%" & search.Text & "%' OR FacultyorStaffID LIKE '%" & search.Text & "%' OR RFID LIKE '%" & search.Text & "%' OR College LIKE '%" & search.Text & "%'" 
      searchfrm2.Show() 
      da.SelectCommand = cmd 
      dt.Clear() 
      da.Fill(dt) 
      cn.Close() 
     End If 
    End With 

Answer 1

我假设你需要显示两个表例如两个要显示FirstName和FamilyName然后你只需要运行1个查询如下

"Select 1 as [type] , FirstName, LastName from Students "+ 
" WHERE Familyname = '" & search.Text & "' OR Firstname = '" & search.Text & "' OR StudentID = '" & search.Text & "' OR RFID = '" & search.Text & "'"+ 
+" Union All " 
+" Select 2 , FirstName, LastName from FactandStaff)"+ 
+"WHERE Familyname LIKE '%" & search.Text & "%' OR Firstname LIKE '%" & search.Text & "%' OR FacultyorStaffID LIKE '%" & search.Text & "%' OR RFID LIKE '%" & search.Text & "%' OR College LIKE '%" & search.Text & "%'" 

PS一般的数据：而不是像这样使用string.format，如下所示

String.Format("Select 1 as [type], FirstName, LastName from Students where Familyname = '{0}' or Firstname = '{0}' OR StudentID = {0} OR RFID = '{0}' \r Union All \r Select 2,FirstName, LastName from FactandStaff WHERE Familyname LIKE '%{0}%' OR Firstname LIKE '%{0}%' OR FacultyorStaffID LIKE '%{0}%' OR RFID LIKE '%{0}%' OR College LIKE '%{0}%'", search.Text);