vb.net数据列表 vbnet操作数据库
用vb.net 怎样建立一个mdb数据库及一张表
首先在项目的VB.NET界面,使用菜单【项目】--【添加引用】--【COM】
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选择 Microsoft ADO Ext. 2.x for DDL and Security
然后单击【确定】,完成引用。
完整代码如下:
Imports ADOX
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'创建空的access数据库文件--数据库文件.mdb,密码为123
Dim Mycat As Catalog = New Catalog()
Mycat.Create("Provider=Microsoft.Jet.OLEDB.4.0;Jet OLEDB:Engine Type=5;Data Source= 数据库文件.mdb;Jet OLEDB:Database Password=123")
'以下代码创建一个名为“实验数据表”
Dim MyTable As ADOX.Table = New ADOX.Table '定义新表
MyTable.Name = "实验数据表" '表命名
'给表“实验数据表” 创建一个字符串字段,字段名“姓名”
MyTable.Columns.Append("姓名", , ADOX.DataTypeEnum.adWChar)
'给表“实验数据表” 创建一个整数字段,字段名“学号”
MyTable.Columns.Append("学号", ADOX.DataTypeEnum.adInteger) '追加一个数字型字段
'给字段“学号”创建一个主键“PimaryKey_Field”
MyTable.Keys.Append("学号", ADOX.KeyTypeEnum.adKeyPrimary, "学号")
Mycat.Tables.Append(MyTable) '把所有的新字段追加到表
MyTable = Nothing
Mycat = Nothing
End Sub
End Class
VB.NET大量数据列表化实时显示用什么控件比较好
接收数据时,使用一个 Label 显示就行了。而且跳过一些数据再显示,例如一秒钟才显示一个数据。
你应该把精力放到领导(或者用户)的意图上,不要纠结技术上的 ListBox。
VB.NET数组或数组列表
Dim TestItem() As String = New String() {"Pickle", "Pineapple", "Papaya"} '创建数组 并赋值
Dim TestShoppingList As String = Join(TestItem, " = ") 'Join 就是字符联接函数 后面的 =号 可选 为空值就把所有的字符串在一起 本例用=号 就是把 所有数组的值用 =号联接起来
MsgBox(TestShoppingList) '显示结果值
'这例子 就一个函数可以解决 就不发图片了
希望能帮到你 你慢慢研究吧 有问题可以找我
看到的 爱好者 多顶我一下 谢谢呵呵
利用VB.NET实现导出DataTable数据到excel中,各位大侠帮帮忙,最好有源码,谢谢,江湖救急
刚好写了个Helper类,你试验一下DataTable2Exce(这个方法代码如下:
Imports System.IO
Imports System.Data
Imports System.Data.OleDb
Public MustInherit Class ExcelHelper
Private Shared Function buildConnStr(excelFilePath As String) As String
Dim excelFileInfo As New System.IO.FileInfo(excelFilePath)
Dim constr As String
If excelFileInfo.Extension = ".xlsx" Then
constr = String.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 12.0 Xml;HDR=YES;IMEX=1'", excelFilePath)
Else
constr = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties='Excel 8.0;HDR=Yes;IMEX=1'", excelFilePath)
End If
Return constr
End Function
'将datatable导入到excel
Public Shared Function DataTable2Excel(dt As DataTable, excelFilePath As String) As Boolean
If File.Exists(excelFilePath) Then
Throw New Exception("该文件已经存在!")
End If
If dt.TableName.Trim.Length = 0 Or dt.TableName.ToLower = "table" Then
dt.TableName = "Sheet1"
End If
Dim colCount As Integer = dt.Columns.Count
Dim pa(colCount - 1) As OleDb.OleDbParameter
Dim tableStructStr As String = "Create Table " dt.TableName "("
Dim connString As String = buildConnStr(excelFilePath)
Dim objconn As New OleDbConnection(connString)
Dim objcmd As New OleDbCommand
objcmd.Connection = objconn
Dim dataTypeList As New ArrayList
dataTypeList.Add("System.Decimal")
dataTypeList.Add("System.Double")
dataTypeList.Add("System.Int16")
dataTypeList.Add("System.Int32")
dataTypeList.Add("System.Int64")
dataTypeList.Add("System.Single")
Dim i As Integer = 0
For Each col As DataColumn In dt.Columns
If dataTypeList.IndexOf(col.GetType.ToString) 0 Then
pa(i) = New OleDbParameter("@" col.ColumnName, OleDbType.Double)
objcmd.Parameters.Add(pa(i))
If i + 1 = colCount Then
tableStructStr += col.ColumnName + " double)"
Else
tableStructStr += col.ColumnName + " double,"
End If
Else
pa(i) = New OleDbParameter("@" col.ColumnName, OleDbType.VarChar)
objcmd.Parameters.Add(pa(i))
If i + 1 = colCount Then
tableStructStr += col.ColumnName + " VarChar)"
Else
tableStructStr += col.ColumnName + " VarChar,"
End If
End If
i += 1
Next
Try
objcmd.CommandText = tableStructStr
If objconn.State = ConnectionState.Closed Then objconn.Open()
objcmd.ExecuteNonQuery()
Catch ex As Exception
Throw ex
End Try
Dim InsertSql_1 As String = "Insert into " + dt.TableName + " ("
Dim InsertSql_2 As String = " Values ("
Dim InsertSql As String = ""
For colID As Integer = 0 To colCount - 1 Step 1
If colID + 1 = colCount Then
InsertSql_1 += dt.Columns(colID).ColumnName ")"
InsertSql_2 += "@" + dt.Columns(colID).ColumnName + ")"
Else
InsertSql_1 += dt.Columns(colID).ColumnName + ","
InsertSql_2 += "@" + dt.Columns(colID).ColumnName + ","
End If
Next
InsertSql = InsertSql_1 + InsertSql_2
For rowID As Integer = 0 To dt.Rows.Count - 1 Step 1
For colID = 0 To dt.Columns.Count - 1
If pa(colID).DbType = DbType.Double And dt.Rows(rowID)(colID).ToString.Trim = "" Then
pa(colID).Value = 0
Else
pa(colID).Value = dt.Rows(rowID)(colID).ToString.Trim
End If
Next
Try
objcmd.CommandText = InsertSql
objcmd.ExecuteNonQuery()
Catch ex As Exception
Throw ex
End Try
Next
Try
If objconn.State = ConnectionState.Open Then objconn.Close()
Catch exp As Exception
Throw exp
End Try
Return True
End Function
' 获取Excel文件数据表列表Sheets
Public Shared Function GetExcelTables(ExcelFileName As String) As ArrayList
'Dim sheets As New List(Of String)
'conn.Open()
'Dim dt As DataTable = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, Nothing)
'For Each r In dt.Rows
' sheets.Add(r("TABLE_NAME"))
'Next
'conn.Close()
'Return sheets
Dim dt As DataTable
If Not File.Exists(ExcelFileName) Then
Throw New Exception("指定的Excel文件不存在")
Return Nothing
End If
Dim tableList As New ArrayList
Using conn As OleDbConnection = New OleDbConnection(buildConnStr(ExcelFileName))
Try
conn.Open()
dt = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, New Object() {Nothing, Nothing, Nothing, "TABLE"})
Catch ex As Exception
Throw ex
End Try
For i As Integer = 0 To dt.Rows.Count - 1
Dim tableName As String = dt.Rows(i)(2).ToString.Trim.TrimEnd("$")
If tableList.IndexOf(tableName) 0 Then tableList.Add(tableName)
Next
End Using
Return tableList
End Function
'将Excel文件导出至DataTable(第一行作为表头)
Public Shared Function InputFromExcel(ExcelFileName As String, TableName As String) As DataTable
If Not File.Exists(ExcelFileName) Then
Throw New Exception("指定的Excel文件不存在")
End If
Dim tableList As ArrayList = GetExcelTables(ExcelFileName)
If tableList.IndexOf(TableName) 0 Then
TableName = tableList(0).ToString.Trim
End If
Dim dt As New DataTable
Dim conn As New OleDbConnection(buildConnStr(ExcelFileName))
Dim cmd As New OleDbCommand("select * from [" TableName "$]", conn) '调试是否需要$
Dim adapter As New OleDbDataAdapter(cmd)
Try
If conn.State = ConnectionState.Closed Then conn.Open()
adapter.Fill(dt)
Catch ex As Exception
Throw ex
Finally
If conn.State = ConnectionState.Open Then conn.Close()
End Try
Return dt
End Function
'查询excel文件中的一个数据
Public Shared Function ReadOneDataFromExcel(ExcelFileName As String, TableName As String, sql As String) As Object
If Not File.Exists(ExcelFileName) Then
Throw New Exception("指定的Excel文件不存在")
End If
Dim tableList As ArrayList = GetExcelTables(ExcelFileName)
If tableList.IndexOf(TableName) 0 Then
TableName = tableList(0).ToString.Trim
End If
Dim dt As New DataTable
Dim conn As New OleDbConnection(buildConnStr(ExcelFileName))
Dim cmd As New OleDbCommand(sql, conn) '调试是否需要$
Dim ret As Object
Try
If conn.State = ConnectionState.Closed Then conn.Open()
ret = cmd.ExecuteScalar()
Catch ex As Exception
Throw ex
Finally
If conn.State = ConnectionState.Open Then conn.Close()
End Try
Return ret
End Function
'获取Excel文件指定数据表的数据列表columnNames
Public Shared Function GetExcelTableColumns(ExcelFileName As String, TableName As String) As ArrayList
Dim dt As DataTable
If Not File.Exists(ExcelFileName) Then
Throw New Exception("指定的Excel文件不存在")
Return Nothing
End If
Dim ColList As New ArrayList
Using conn As OleDbConnection = New OleDbConnection(buildConnStr(ExcelFileName))
Try
conn.Open()
dt = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Columns, New Object() {Nothing, Nothing, TableName, Nothing})
Catch ex As Exception
Throw ex
End Try
For i As Integer = 0 To dt.Rows.Count - 1
Dim ColName = dt.Rows(i)("Column_Name").ToString().Trim()
ColList.Add(ColName)
Next
End Using
Return ColList
End Function
End Class
vb.net中的list怎样用数组添加列表项
list1.additem j 意思就是把j添加至list1列表中,这是在一个for 循环中,循环了10次,添加了10次 j,即 list1 中 有10列分别为:1,3,6,10,15,21,28,36,45,55
下面又来了一个循环, list1.removeitem 删除列,删除的是 list1.listcount - i ,list1.listcount 就是总列数为10,减去 i ,i 是1到4,即10-1,9-2,8-3,7-4 每减掉一次,list1.listcount 就少了一条记录。
(注意,list1.listcount-1 是最后一条记录)
减掉了第 9,7,5,3列
剩余为 1,3,6,15,28,45
结果为:3,15,28
'ListCount返回列表框中的项目总数
'ListCount-1是列表框中最后一个项目的索引号
'亏你提醒了,我写错了,上面修改了,第一个索引为0,最后一个为9.
'也就是,问题所问的第二列的索引为1,第四列的索引为3...
VB.Net中datagridview如何数据表
你可以在SQL语句里面把列名变为中文名 再放到DATAGRID里面啊
如 SELECT 字段1 AS 某某1 ,字段2 AS 某某2 FROM 某表
你的串号我已经记下,采纳后我会帮你制作
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