学生信息系统模块注释

Public fMainform As frmMain   '他们是类型变量Public UserName As String   '定义全局变量已知道登录用户信息 Sub Main()    Dim fLogin As New frmLogin    fLogin.Show vbModal             '显示登录窗体实例       'OK为fMainForm类的成员   If Not fLogin.OK Then  '如果是flogin        'Login Failed so exit app        End    End If    Unload fLogin    Set fMainform = New frmMain    fMainform.Show    '显示主窗体实例End Sub''以文件DSN标记，访问ODBC数据源Public Function Connectstring() As String' Connectstring = "Provider=SQLOLEDB;server=192.168.26.43;database=Student;UID=sa;PWD=1"，这是远程异地发布的代码    Connectstring = "FileDSN=studentinfo.dsn;UID=sa;PWD=1"End FunctionPublic Function ExecuteSQL(ByVal SQL As String, MsgString As String) As ADODB.Recordset '执行sql语句'传递参数SQL传递查询语句，msgstring传递查询信息'executes SQL and returns Recordset   Dim cnn As ADODB.Connection   Dim rst As ADODB.Recordset   Dim sTokens() As String   On Error GoTo ExecuteSQL_Error   sTokens = Split(SQL)   '用split函数产生一个包含各字串的数组   Set cnn = New ADODB.Connection   ‘建立连接   cnn.Open Connectstring       ’打开连接'instr返回要截取的字符串在源字符串中的位置。instr是一个非常好用的字符串处理函数，几乎所有的字符串分隔都用到此函数。'UCase用来将小写字母转化为大写字母   If InStr("INSERT,DELETE,UPDATE", UCase$(sTokens(0))) Then            '非Select语句      cnn.Execute SQL   '数据量不大时，可以在连接上，直接执行SQL语句      MsgString = sTokens(0) & " query successful"      '虽然MsgString不是返回值，但传递方式是ByRef，实参地址和这个地址相同   Else                                                                 'Select语句      Set rst = New ADODB.Recordset      rst.Open Trim$(SQL), cnn, adOpenKeyset, adLockOptimistic      '得到临时表，游标指向第一条记录      '返回记录集      Set ExecuteSQL = rst      MsgString = "查询到" & rst.RecordCount & " 条记录 "   End If'错误处理executesql_exit:   Set rst = Nothing  '清空数据库   Set cnn = Nothing  '中断连接   Exit Function'错误类型判断ExecuteSQL_Error:   MsgString = "查询错误: " & Err.Description   Resume executesql_exitEnd FunctionPublic Function testtxt(txt As String) As Boolean    If Trim(txt) = "" Then    '定义一个testtxt函数，检查输入内容是否为空        testtxt = False     Else        testtxt = True    End IfEnd Function