如何在表单加载中显示数据库中的递增值 [英] how to show incremented value from databse in form load
问题描述
这里在表单加载事件即时尝试从值sql server数据库ID列中取值并希望
在文本框控件中显示最大值(ID)+1
这里是visual studio,当我开始调试它的开始编译没有任何错误但几秒后它会自动停止调试
帮我解决我的代码中的问题
$ / b
公共类别FrmAdddonor
Dim con作为新的SqlConnection(数据源= Tarun-PC;初始目录= bdsdb;集成安全性=真的)
Private Sub FrmAdddonor_Load(发件人作为对象,e作为EventArgs)处理MyBase.Load
txtdonorID.Enabled = False
Dim number As Integer
con.Open()
Dim Str As String =从tbldonor选择max(ID)+1;
Dim com As New SqlCommand(Str,con)
Dim reader As SqlDataReader = com.ExecuteReader()
如果reader.Read()那么
number = reader(ID)。ToString()
txtdonorID.Text = number
reader.Close()
con.Close( )
结束如果
结束Sub
你有一些错误在你的代码中:
-选择语句应该是:从tbldonor选择max(ID)为MAX
-然后将Dim temp作为整数; temp = DirectCast(reader(MAX),Integer)+ 1;
-end finally:txtdonorID.Text = temp.ToString();
< pre lang =vb> 公共 功能 maxuse() as integer
con.Open()
sql =& quot; select IIF(ISNULL(MAX(sms_count)),来自sms_master& quot;的 0 ,MAX(sms_count))
Com = 新 OleDb.OleDbCommand(sql,con)
maxuse = Com.ExecuteScalar()
&#39; If _maxno =& quot;& amp; H0& quot; 然后
&#39; _maxno = 0
&#39;结束如果
Com.ExecuteNonQuery( )
Com.Dispose()
con.Close()
结束 Sub < / pre >
私人 Sub Form1_Load( ByVal sender As Object , ByVal e As System.EventArgs)句柄 我 .Load
textbox1.text = maxuse()+ 1
结束 Sub
Here in form load event i m trying to take value form sql server database ID column and want to
display max(ID)+1 in textbox control
here in visual studio when i start debug its start compiling without any error but after few seconds it automatically stop debugging
help me whats the issue in my code
Public Class FrmAdddonor
Dim con As New SqlConnection(Data Source=Tarun-PC;Initial Catalog=bdsdb;Integrated Security=True)
Private Sub FrmAdddonor_Load(sender As Object, e As EventArgs) Handles MyBase.Load
txtdonorID.Enabled = False
Dim number As Integer
con.Open()
Dim Str As String =select max(ID)+1 from tbldonor;
Dim com As New SqlCommand(Str, con)
Dim reader As SqlDataReader = com.ExecuteReader()
If reader.Read() Then
number = reader("ID").ToString()
txtdonorID.Text = number
reader.Close()
con.Close()
End If
End Sub
You have some errors in your code:
-the select statement should be: "select max(ID) as MAX from tbldonor"
-then Dim temp as integer; temp = DirectCast(reader("MAX"), Integer) + 1;
-end finally: txtdonorID.Text = temp.ToString();
Public Function maxuse() as integer con.Open() sql = "select IIF(ISNULL(MAX(sms_count)), 0, MAX(sms_count)) from sms_master" Com = New OleDb.OleDbCommand(sql, con) maxuse = Com.ExecuteScalar() 'If _maxno = "&H0" Then ' _maxno = 0 'End If Com.ExecuteNonQuery() Com.Dispose() con.Close() End Sub</pre>
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load textbox1.text = maxuse() + 1 End Sub
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