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
答案 0 :(得分:0)
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
答案 1 :(得分:-1)
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