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Visual studio 返回的值超过1的ExecuteScalar()_Visual Studio - Fatal编程技术网

Visual studio 返回的值超过1的ExecuteScalar()

Visual studio 返回的值超过1的ExecuteScalar(),visual-studio,Visual Studio,我想返回我的查询=“显示数据库” 然后这是我的代码 dim conn as conn.connectionstring = Myconnection dim Mydb as new Mysql.data.mysqlclient.mysqlcommand(myquery,conn) conn.open textbox2.text = convert.tostring(mydb.excutescalar()) 我的输出是: 信息模式 mysql 试验 现在我找到了一种方法 下面的代码 Dim m

我想返回我的查询=“显示数据库” 然后这是我的代码

dim conn as conn.connectionstring = Myconnection
dim Mydb as new Mysql.data.mysqlclient.mysqlcommand(myquery,conn)
conn.open
textbox2.text = convert.tostring(mydb.excutescalar())
我的输出是:

  • 信息模式
  • mysql
  • 试验
    • 现在我找到了一种方法

      下面的代码

      Dim myQuery As String = "show databases"
      TextBox1.Text = "localhost"
          constring = "server=" & TextBox1.Text & ";" _
          & "uid=root;" _
          & "pwd=admin;" _
          & "database=mysql;"
          Try
              conn.ConnectionString = constring
              Dim myDb As New MySql.Data.MySqlClient.MySqlCommand(myQuery, conn)
              conn.Open()
              ComboBox1.Text = "select database"
              'myDb.Connection.Open()
              'TextBox2.Text = TextBox2.Text + Convert.ToString(myDb.ExecuteScalar())
              Dim myReader As MySql.Data.MySqlClient.MySqlDataReader = myDb.ExecuteReader()
              Try
                  While myReader.Read
                      ComboBox1.Items.Add(myReader.GetString(0))
                  End While
              Finally
                  myReader.Close()
                  conn.Close()
              End Try
      
          Catch ex As Exception
              MessageBox.Show(ex.Message)
          End Try
      
      然后是我的输出

      ExecuteScalar不能返回多个结果。Use ExecuteReaderOh ok,但Use execute reader只能是“选择”