VB.net 连接 MySql,Use MySql.Data.dll

发布时间：2020-12-16 22:43:25 所属栏目：大数据来源：网络整理

导读：下载一个叫 mysql-connector-net 的库文件安装后，会得到一下东西 MySql.Data.dll ，.net 与MySql 连接的桥梁，很好用 MySql.Data.dll ，源码，C# 的，你可以试着完善它 C#和VB.net 的示例程序。在项目中引用 MySql.Data.dll 再来个 Imports MySql.Data.My

下载一个叫 mysql-connector-net 的库文件
安装后，会得到一下东西
MySql.Data.dll ，.net 与MySql 连接的桥梁，很好用
MySql.Data.dll ，源码，C# 的，你可以试着完善它
C#和VB.net 的示例程序。
在项目中引用 MySql.Data.dll
再来个 Imports MySql.Data.MySqlClient 就可以使用了

里面有一些对MySql 数据库的一般操作，很容易上手。

下面是我总结出的MySql命令语句，留个档~~

连接：
server={0};user id={1}; password={2}; database=mysql; pooling=false;port={3}

获取：
SELECT * FROM login where UserName='{0}' and Password='{1}'
这里值得注意，文本型的在 Sql 2000 中要使用 like 比较
select ID from login order by ID desc limit 1
可以获得最后一个ID

更新：
UPDATE login SET logintimes='{0}',LastDateTime='{1}' where UserName='{2}'

插入：
INSERT INTO login (id,username,password) VALUES ('{0}','{1}','{2}')

删除：
delete FROM med_entry where ID='{0}'

下面几个自己写的函数，很有用处

'执行 MySql 语句，支持多行。没有返回值
Function ExecuteMySqlCMD(ByRef iconn As MySqlConnection,ByRef MySqlCMD As String,Optional ByRef Err As String = "") As Boolean
MySqlCMD = Strings.Replace(MySqlCMD,Chr(13),"")
MySqlCMD = Strings.Replace(MySqlCMD,Chr(10),"")
Err = ""
Dim reader As MySqlDataReader = Nothing
Dim cmdList() As String
Dim cmd As MySqlCommand = Nothing
Dim i As Integer
cmdList = Strings.Split(MySqlCMD,";")

If cmdList IsNot Nothing Then
Try
For i = 0 To cmdList.Length - 1
If cmdList(i) = "" Then Continue For
cmd = New MySqlCommand(cmdList(i),iconn)
reader = cmd.ExecuteReader()
reader.Close()
Next
Return True
Catch ex As MySqlException
Err = ex.Message
End Try
End If
Return False
End Function

'执行 MySql 语句，只能一行。返回 DataTable,MySqlDataAdapter,MySqlCommandBuilder
Function ExecuteMySqlCMD(ByRef iconn As MySqlConnection,ByRef iDataTable As DataTable,Optional ByRef iMySqlDataAdapter As MySqlDataAdapter = Nothing,Optional ByRef iMySqlCommandBuilder As MySqlCommandBuilder = Nothing,"")
Err = ""

Dim cmdList() As String
cmdList = Strings.Split(MySqlCMD,";")
If cmdList IsNot Nothing Then
Try
If cmdList(0) = "" Then Exit Try
iDataTable = New DataTable
iMySqlDataAdapter = New MySqlDataAdapter(cmdList(0),iconn)
iMySqlCommandBuilder = New MySqlCommandBuilder(iMySqlDataAdapter)
iMySqlDataAdapter.Fill(iDataTable)
Return True
Catch ex As MySqlException
Err = ex.Message
End Try
End If
Return False
End Function

'检查数据库是否存在
Function CheckDataBase(ByRef iconn As MySqlConnection,ByRef DataBaseName As String,Optional ByRef Err As String = "") As Boolean
Dim reader As MySqlDataReader = Nothing
DataBaseName = DataBaseName.ToLower
Err = ""
Dim cmd As New MySqlCommand("SHOW DATABASES",iconn)
Try
reader = cmd.ExecuteReader()

While (reader.Read())
If reader.GetString(0).ToLower = DataBaseName Then
Return True
End If
End While

Catch ex As MySqlException
Err = ex.Message
Finally
If Not reader Is Nothing Then reader.Close()
End Try
Return False
End Function

'检查数据表是否存在 Function CheckTable(ByRef iconn As MySqlConnection,ByVal TableName As String,Optional ByRef Err As String = "") As Boolean Dim reader As MySqlDataReader = Nothing DataBaseName = DataBaseName.ToLower TableName = TableName.ToLower Err = "" iconn.ChangeDatabase(DataBaseName) Dim cmd As New MySqlCommand("SHOW TABLES",iconn) Try reader = cmd.ExecuteReader() While (reader.Read()) If reader.GetString(0).ToLower = TableName Then Return True End If End While Catch ex As MySqlException Err = ex.Message Finally If Not reader Is Nothing Then reader.Close() End Try Return False End Function

（编辑：李大同）

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