Question

我有一个SQL表，看起来像：

+-------------------+
| id   member   req |
+-------------------+
| 1    Jim      0   |
| 2    Mary     0   |
| 3    Hunter   0   |
+-------------------+

我需要通过Visual Basic 2010中的vb.net应用程序（WinForms）获取某个成员的id。

让我们说我想要 Mary id。返回 Mary 的<{1}}的SQL查询是什么？

什么是查询？

-------------------------------------------- ------------------------------------

可能的查询代码：

id是我在数据库中查找以获取成员'My.Settings.username的名称。

id

Answer 1

首先，下载MySQL connector。

其次，添加对项目的MySQL连接的引用。

第三，导入你将使用许多类的命名空间来减少输入（在.vb文件的顶部）：

Imports MySql.Data.MySqlClient

最后在Form的Load事件处理程序（或您希望在标签中显示ID的其他事件处理程序）中：

'Change to your specific connection string.
Dim strConnectionString As String = "Database=YourDatabaseName;Data Source=localhost;User Id=YourUser;Password=YourPassword"

Dim sqlConnection As New MySqlConnection(strConnectionString)

Dim strCommandText = "SELECT id FROM members WHERE member = @Member"

'Assumes that the ID field is an INT type.  Use a Long type if the type is a BIGINT.
Dim intID as Integer

Try

    'Open the connection.
    sqlConnection.Open()

    'Create a command to get the ID.
    Dim sqlCommand As MySqlCommand = New MySqlCommand(strCommandText, sqlConnection)

    'It is always a good idea to use parameters.
    sqlCommand.Parameters.AddWithValue("@Member", My.Settings.username)

    vagueID.Text = Convert.ToString(sqlCommand.ExecuteScalar())

Catch ex As Exception
    'Error handling goes here.
    MsgBox(ex.Message)
Finally
    'Always close the connection!
    sqlConnection.Close()
End Try

Answer 2

MySQLCon = New MySqlConnection MySQLCon.ConnectionString = "Database=localhost;Data Source=host;User Id=root;Password=root" Dim READER As MySqlDataReader Dim COMMAND As MySqlCommand Try MySQLCon.Open() Dim SQLID As String = "SELECT id FROM members WHERE member='" & My.Settings.username & "'" COMMAND = New MySqlCommand(SQLID, MySQLCon) READER = COMMAND.ExecuteReader() While READER.Read vagueID.Value2 = READER.GetInt32("id") End While MySQLCon.Close() MySQLCon.Dispose() Catch ex As Exception 'Do Something End Try

根据vb.net的会员名称从数据库中获取值？

2 个答案: