Dim cn As New ADODB.Connection
Dim rs As New ADODB.Recordset
Dim sql As String
Dim sqlWhere As String
Private Sub Command1_Click() '查询
    If cn.State = adStateOpen Then cn.Close
    If rs.State = adStateOpen Then rs.Close
cn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "/db.mdb;Persist Security Info=False"
 sqlWhere = vbNullString
    If Trim(Text1.Text) = "" Then
           sqlWhere  = sqlWhere &  年级 like '" & Combo1.Text & "' and 班级 like '" & Combo2.Text & "'"
    End If
    If Trim(Text1.Text) <> 0 Then
        sqlWhere  = sqlWhere &  年级 like '" & Combo1.Text & "' and 班级 like '" & Combo2.Text & "' and 姓名 like '" & Text1.Text & "'
    End If
 
    sql = "select * from 档案 " & sqlWhere
 
    rs.Open sql, cn, 3, 3   出现FORM子语法错误