VB.net 连接 MySql,Use MySql.Data.dll

下载一个叫 mysql-connector-net-5.0.5.zip 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 MySqlCMD As String, ByRef iDataTable As DataTable, Optional ByRef iMySqlDataAdapter As MySqlDataAdapter = Nothing, Optional ByRef iMySqlCommandBuilder As MySqlCommandBuilder = Nothing, Optional ByRef Err As String = "") As Boolean
MySqlCMD = Strings.Replace(MySqlCMD, Chr(13), "")
MySqlCMD = Strings.Replace(MySqlCMD, Chr(10), "")
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, ByRef DataBaseName As String, 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