【VB实例】登录功能 连接Access/SQL Server数据库 Visual Basic 编程

登录1
Private Sub Command登录_Click()
If Text密码 = "" Then
MsgBox "登录密码不能为空"
Exit Sub
End If
If Text密码 = "abc123" Then
MsgBox "登录成功"
Unload Form登录1
Form系统主页1.Show 1
Else
MsgBox "登录密码不正确"
End If
End Sub
登录2
Public login_count As Long
Private Sub Command登录_Click()
Dim 账号text As String '定义变量存储账号
Dim 密码text As String '定义变量存储密码
If Trim(Text账号) <> "" Then '输入账号不能为空
账号text = Me.Text账号 '存储录入账号到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "账号不能为空!"
Exit Sub
End If
If Trim(Me.Text密码) <> "" Then '输入密码不能为空
If Len(Trim(Me.Text密码)) < 6 Then
MsgBox "密码长度不能小于6位!"
Exit Sub
End If
密码text = Me.Text密码 '存储录入密码到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "密码不能为空!"
Exit Sub
End If
'-账号密码验证
Dim login_conn As New ADODB.Connection '连接到ACCESS数据库
With login_conn 'mdb格式连接
.ConnectionString = "Provider = microsoft.jet.oledb.4.0;data source=" & App.Path & "\db_data.mdb;Jet OLEDB:DataBase password=abc123;persist security info=false"
.Open
End With
Dim login_rs As New ADODB.Recordset
Dim login_sql As String
login_sql = "select * from 用户表 where 账号= '" & Me.Text账号 & "' and 密码='" & Me.Text密码 & "'" '查询用户表
login_rs.Open login_sql, login_conn, adOpenDynamic, adLockOptimistic
If login_rs.EOF = False Then '循环表的内容
On Error Resume Next
user_name = login_rs.Fields("账号").Value '账号赋值到公共变量
MsgBox "登录成功"
Unload Me '关闭登录窗体
Form系统主页2.Show 1
Else
MsgBox "账号或密码错误,请重新登录"
login_count = login_count + 1 '登录错误3次,退出
If login_count = 3 Then
MsgBox "账号或密码错误达3次"
Unload Me
End If
End If
login_rs.Close
Set login_rs = Nothing
login_conn.Close
Set login_conn = Nothing
Exit Sub
登录3
Public login_count As Long
Private Sub Command登录_Click()
Dim 账号text As String '定义变量存储账号
Dim 密码text As String '定义变量存储密码
If Trim(Text账号) <> "" Then '输入账号不能为空
账号text = Me.Text账号 '存储录入账号到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "账号不能为空!"
Exit Sub
End If
If Trim(Me.Text密码) <> "" Then '输入密码不能为空
If Len(Trim(Me.Text密码)) < 6 Then
MsgBox "密码长度不能小于6位!"
Exit Sub
End If
密码text = Me.Text密码 '存储录入密码到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "密码不能为空!"
Exit Sub
End If
'-账号密码验证
Dim login_conn As New ADODB.Connection '连接到ACCESS数据库
With login_conn 'mdb格式连接
.ConnectionString = "Provider = microsoft.jet.oledb.4.0;data source=" & App.Path & "\db_data.mdb;Jet OLEDB:DataBase password=abc123;persist security info=false"
.Open
End With
Dim login_rs As New ADODB.Recordset
Dim login_sql As String
login_sql = "select * from 用户表 where 账号= '" & Me.Text账号 & "'" '查询用户表
login_rs.Open login_sql, login_conn, adOpenDynamic, adLockOptimistic
If login_rs.EOF = False Then '循环表的内容
On Error Resume Next
If 密码text = login_rs.Fields("密码").Value Then
user_name = login_rs.Fields("账号").Value '账号赋值到公共变量
MsgBox "登录成功"
Unload Me '关闭登录窗体
Form系统主页3.Show 1
Else
MsgBox "密码错误"
login_count = login_count + 1 '登录错误3次,退出
If login_count = 3 Then
MsgBox "密码错误达3次"
Unload Me
End If
End If
Else
MsgBox "账号不存在"
End If
login_rs.Close
Set login_rs = Nothing
login_conn.Close
Set login_conn = Nothing
Exit Sub
登录失败错误:
MsgBox Err.Description
End Sub
登录4
Private Sub Command登录_Click()
Dim 账号text As String '定义变量存储账号
Dim 密码text As String '定义变量存储密码
If Trim(Text账号) <> "" Then '输入账号不能为空
账号text = Me.Text账号 '存储录入账号到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "账号不能为空!"
Exit Sub
End If
If Trim(Me.Text密码) <> "" Then '输入密码不能为空
If Len(Trim(Me.Text密码)) < 6 Then
MsgBox "密码长度不能小于6位!"
Exit Sub
End If
密码text = Me.Text密码 '存储录入密码到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "密码不能为空!"
Exit Sub
End If
'-账号密码验证
Adodc1.RecordSource = "Select * from 用户表 Where 账号='" & 账号text & "'" '筛选ADO控件记录
Adodc1.Refresh
If Adodc1.Recordset.RecordCount = 1 Then '
If 密码text = Adodc1.Recordset.Fields("密码").Value Then
user_name = 账号text '账号赋值到公共变量
MsgBox "登录成功"
Unload Me '关闭登录窗体
Form系统主页3.Show 1
Else
MsgBox "密码错误"
login_count = login_count + 1 '登录错误3次,退出
If login_count = 3 Then
MsgBox "密码错误达3次"
Unload Me
End If
End If
Else
MsgBox "账号不存在"
End If
Exit Sub
登录失败错误:
MsgBox Err.Description
End Sub
登录5
Public login_count As Long
Private Sub Command登录_Click()
Dim 账号text As String '定义变量存储账号
Dim 密码text As String '定义变量存储密码
If Trim(Text账号) <> "" Then '输入账号不能为空
账号text = Me.Text账号 '存储录入账号到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "账号不能为空!"
Exit Sub
End If
If Trim(Me.Text密码) <> "" Then '输入密码不能为空
If Len(Trim(Me.Text密码)) < 6 Then
MsgBox "密码长度不能小于6位!"
Exit Sub
End If
密码text = Me.Text密码 '存储录入密码到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "密码不能为空!"
Exit Sub
End If
'-账号密码验证
Dim login_conn As New ADODB.Connection '连接到ACCESS数据库
With login_conn '连接
.ConnectionString = "Provider=SQLOLEDB.1;Persist Security Info=False;User ID=sa;pwd=123123;Initial Catalog=test1;Data Source=(local)"
.Open
End With
Dim login_rs As New ADODB.Recordset
Dim login_sql As String
login_sql = "select * from 用户表 where 账号= '" & Me.Text账号 & "' and 密码='" & Me.Text密码 & "'" '查询用户表
login_rs.Open login_sql, login_conn, adOpenDynamic, adLockOptimistic
If login_rs.EOF = False Then '循环表的内容
'On Error Resume Next
user_name = login_rs.Fields("账号").Value '账号赋值到公共变量
MsgBox "登录成功"
Unload Me '关闭登录窗体
Form系统主页3.Show 1
Else
MsgBox "账号或密码错误,请重新登录"
login_count = login_count + 1 '登录错误3次,退出
If login_count = 3 Then
MsgBox "账号或密码错误达3次"
Unload Me
End If
End If
login_rs.Close
Set login_rs = Nothing
login_conn.Close
Set login_conn = Nothing
Exit Sub
登录6
Public login_count As Long
Private Sub Command登录_Click()
Dim 账号text As String '定义变量存储账号
Dim 密码text As String '定义变量存储密码
If Trim(Text账号) <> "" Then '输入账号不能为空
账号text = Me.Text账号 '存储录入账号到变量中(可拓展更多判断,如字符长度等)
Else
MsgBox "账号不能为空!"
Exit Sub
End If
If Trim(Me.Text密码) <> "" Then '输入密码不能为空
If Len(Trim(Me.Text密码)) < 6 Then
MsgBox "密码长度不能小于6位!"
Exit Sub
End If
密码text = Me.Text密码 '存储录入密码到变量中
Else
MsgBox "密码不能为空!"
Exit Sub
End If
'-账号密码验证
Adodc1.RecordSource = "Select * from 用户表 Where 账号='" & 账号text & "'" '筛选ADO控件记录
Adodc1.Refresh
If Adodc1.Recordset.RecordCount = 1 Then '
' MsgBox 密码text & Adodc1.Recordset.Fields("密码").Value
Dim A1 As String
A1 = CStr(Adodc1.Recordset.Fields("密码").Value)
If 密码text = Trim(A1) Then
user_name = 账号text '账号赋值到公共变量
MsgBox "登录成功"
Unload Me '关闭登录窗体
Form系统主页3.Show 1
Else
MsgBox "密码错误"
login_count = login_count + 1 '登录错误3次,退出
If login_count = 3 Then
MsgBox "密码错误达3次"
Unload Me
End If
End If
Else
MsgBox "账号不存在"
End If
Exit Sub
登录失败错误:
MsgBox Err.Description
End Sub
系统主页
Private Sub Form_Load()
Text账号.Text = user_name
End Sub
公共变量
Public user_name As String '记录登录账号