mysql事务(提交和回滚)

Question

下面是我用于 MySqlTransaction 的代码，它运行得很好...... 但问题是因为我使用的是 mysqlcommand 的单个实例，所以我必须在其中使用唯一的 PARAMETER。这破坏了我的查询。有没有其他方法可以做....

我尝试在每次查询后处理 cmd 但没有用.. :(

---

          con.Open()
            Dim sqlTran As MySqlTransaction = con.BeginTransaction()
            Dim cmd As MySqlCommand = con.CreateCommand()
            cmd.Transaction = sqlTran
            Dim str As String = Nothing
            Try
                cmd.CommandText = "SELECT myid FROM memaster where    Adate=@adate and ANo=@ano and ASource=@asrc"
                cmd.Parameters.AddWithValue("@adate", txt_bpass_adate.Text)
                cmd.Parameters.AddWithValue("@ano", txt_bpass_af.Text)
                cmd.Parameters.AddWithValue("@asrc", txt_bpass_asource.Text)
                str = cmd.ExecuteScalar()
                'cmd.Dispose()'
                If str Is Nothing Then

                    cmd.CommandText = "Insert into memaster (ADate,ANo,ASource) values (@aDate,@aNo,@aSRC)"
                    cmd.Parameters.AddWithValue("@aDate", txt_bpass_adate.Text)
                    cmd.Parameters.AddWithValue("@aNo", txt_bpass_af.Text)
                    cmd.Parameters.AddWithValue("@aSRC", txt_bpass_asource.Text)

     cmd.ExecuteNonQuery()
    End If
     sqlTran.Commit()

            Catch ex As Exception
                Try
                    sqlTran.Rollback()
                Catch ex1 As Exception

                End Try
            End Try

---

我实际上想在单个事务中触发超过 4 个查询，这样如果出现任何问题我可以回滚它...

如果有人有任何其他方法，请与我分享这个概念......

---

     For index As Integer = 1 To 5
                    cmd.CommandText = "Insert into detail (ID,BNos,SNo) values (@FID1,@BNo,@SeqN1)"
                    cmd.Parameters.AddWithValue("@FID1", str)
                    cmd.Parameters.AddWithValue("@BNo", str1)
                    cmd.Parameters.AddWithValue("@SeqN1", txt_bpass_sqn1.Text)
                    cmd.ExecuteNonQuery()


                Next

Answer 1

要在同一事务中执行多个命令，请确保将事务对象分别分配给每个命令:

Dim selectCmd As MySqlCommand = con.CreateCommand()
Dim insertCmd As MySqlCommand = con.CreateCommand()

selectCmd.CommandText = "SELECT ..."
insertCmd.CommandText = "INSERT ..."

Dim sqlTran As MySqlTransaction = con.BeginTransaction()
Try
  selectCmd.Transaction = sqlTran
  insertCmd.Transaction = sqlTran

  ...selectCmd.ExecuteScalar()...
  ...insertCmd.ExecuteNonQuery()...

  sqlTran.Commit()
Catch
  sqlTran.Rollback()
End Try

正如其他人所提到的，通常在您完成对对象(即 IDisposable)的处理后立即对其进行 Dispose() 处理是个好主意。处置对象后，它们将无法再使用。