vb.net常用语句 vbnet using
VB.NET语句中continue while的用法
VB.NET 2005,已经实现了continue语法，具体是这样操作：
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如果 Continue 语句在 Do...Loop 循环中，请将该语句更改为 Continue Do。
如果 Continue 语句在 For...Next 循环中，请将该语句更改为 Continue For。
如果 Continue 语句在 While...End While 循环中，请将该语句更改为 Continue While。
否则，请移除 Continue 语句。
用法：
For i As Integer = 0 To 100
' If i = 50 跳过 Console.Writeline statement
If i = 50 Then Continue For
Console.WriteLine(i.ToString)
Next
' Do While using Continue statement.
Dim ii As Integer = 1
Do While ii 100
ii += 1
' If ii = 50 跳过 Console.Writeline statement
If ii = 50 Then Continue Do
Console.WriteLine(ii.ToString)
Loop
' While using Continue statement.
Dim iii As Integer = 1
While iii 100
iii += 1
' If iii = 50 跳过 Console.Writeline statement
If iii = 50 Then Continue While
Console.WriteLine(iii.ToString)
End While
vB.Net if 语句
DT.Rows.ToString未必是指结果集中的所有数据，也许只是一行中所有的，或是一列中所有的
保险起见，可以一格格枚举
dim a as boolean=true
Dim row As DataRow
For Each row In DT.Rows
Dim column As DataColumn
For Each column In DT.Columns
if row(column).contains("Agree") then a=false
Next column
Next row
if a then
Me.rblAgReject.Items(0).Enabled = False
else
Me.rblAgReject.Items(0).Enabled = True
end if
VB中的CASE语句
在VB.NET中VB.NET CASE语句就是比较常用的一种，下面是详细的介绍和代码的演示：
1、可以用 Select...Case 语句来替换 If...Then...Else 语句，所不同的是If 和 ElseIf 语句可在每个语句中计算不同的表达式，而 Select 语句对单个表达式只计算一次，然后将其和不同的值比较。
Function bonus(ByVal performance As Integer, _ ByVal salary As Decimal) As Decimal
Select performance
Case 1
Return salary * 0.1
Case 2
Return salary * 0.3
Case 3
Return salary * 0.7
Case 4
Return salary * 0.9
Case 5
Return salary * 1.2
End Select
End Function
2、VB.NET Case语句可包含多个值和某个范围的值，代码案例如下：
Function bonus(ByVal performance As Integer, _ ByVal salary As Decimal) As Decimal
Select performance
Case 1
Return salary * 0.1
Case 2,3
Return salary * 0.3
Case 3 To 7
Return salary * 0.7
Case 8 To 9
Return salary * 0.9
Case Is = 15
Return salary * 1.2
Case Else
Return 0
End Select
End Function
高分求.net里vb语法操作数据库基本语句
Dim Cnn As New Data.OleDb.OleDbConnection
Dim DbAdapter As New Data.OleDb.OleDbDataAdapter
Dim Cmd As New Data.OleDb.OleDbCommand
Dim dsAll As New Data.DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Cnn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\webapp\test\web.mdb"
Cmd.Connection = Cnn
End Sub
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
'插入
Cmd.CommandText = "insert into main (about) values ('" + TextBox1.Text + "')"
UpdateTable()
End Sub
Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
'修改
Dim ids As Integer
ids = 1
Cmd.CommandText = "update main set about='" + TextBox1.Text + "' where id=" + ids.ToString()
UpdateTable()
End Sub
Protected Sub Button3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button3.Click
'删除
Dim ids As Integer
ids = 1
Cmd.CommandText = "delete from main where id=" + ids.ToString()
UpdateTable()
End Sub
Public Sub UpdateTable()
Dim Trans As Data.OleDb.OleDbTransaction
Try
Cnn.Open()
Trans = Cnn.BeginTransaction()
Try
Cmd.Transaction = Trans
Cmd.ExecuteNonQuery()
Trans.Commit()
Catch
Trans.Rollback()
Finally
If (Cnn.State = System.Data.ConnectionState.Open) Then
Cnn.Close()
End If
End Try
Catch
'error message
End Try
End Sub
Protected Sub Button4_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button4.Click
'显示
Cmd.CommandText = "select id, about from main"
DbAdapter.SelectCommand = Cmd
DbAdapter.Fill(dsAll, "table1")
If (dsAll.Tables("table1").Rows.Count 0) Then
TextBox1.Text = dsAll.Tables("table1").Rows(0)("about")
Else
TextBox1.Text = ""
End If
End Sub
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