Question

VB怎么判断用户名和数据库里的有没有重复，如果重复就不会记录

If Text1.Text = "" Then
Label4.Caption = "账号不能为空!"
Label4.ForeColor = vbRed
Exit Sub
End If
If Text2.Text = "" Then
Label4.Caption = "密码不能为空!"
Label4.ForeColor = vbRed
Exit Sub
End If
Call SJK(db) '调用数据库连接
StrSql = "Select * from A1 where MC='" & Text1.Text & "'" '数据表连接字符串
RS.Open StrSql, db, 2, 2 '打开数据表
If RS.EOF = True Then '用户名错误
Label4.Caption = "账号错误!请检查"
Label4.ForeColor = vbRed
RS.Close
db.Close
Exit Sub
Else
If Not RS!MM = Text2.Text Then '用户密码错误
Label4.Caption = "密码错误!请检查"
Label4.ForeColor = vbRed
Else
Form3.Show
Unload Form1

End If
End If
RS.Close
Set RS = Nothing
db.Close
Set db = Nothing
End Sub
这是申明：Public db As New ADODB.Connection '声明数据库连接对象
Public RS As New ADODB.Recordset '声明将来就对象
Public Sub SJK(db) '连接数据库过程
db.ConnectionString = "DRIVER=Microsoft Access Driver (*.mdb);dbQ=" & App.Path & "\A.mdb"
db.Open
End Sub

Answer 1

先查询，看符合记录集的数据是不是0条，是的话就是没有记录

追问

那怎么弄了