189 8069 5689

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:

成都创新互联坚持“要么做到,要么别承诺”的工作理念,服务领域包括:成都做网站、成都网站制作、成都外贸网站建设、企业官网、英文网站、手机端网站、网站推广等服务,满足客户于互联网时代的雁塔网站设计、移动媒体设计的需求,帮助企业找到有效的互联网解决方案。努力成为您成熟可靠的网络建设合作伙伴!

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


网页题目:vb.net常用语句 vbnet using
文章出自:http://jkwzsj.com/article/ddccgic.html

其他资讯