Question

我正在插入一行并使用ADO.Net返回id号： -

command_string = "INSERT INTO [MyDB].[dbo].[MyTable] (THIS, THAT)" & _
                 " OUTPUT inserted.ID_NUMER AS ID_NUMBER " & _
                 "    VALUES ('This', 'That')"

Dim insert_command   As SqlCommand     =
        New SqlCommand(command_string, database_connection)
Dim output_parameter As SqlParameter   =
        New SqlParameter("@id_number", SqlDbType.Int)
Dim transaction      As SqlTransaction =
        database_connection.BeginTransaction(System.Data.IsolationLevel.Serializable)
insert_command.Transaction = transaction
output_parameter.Direction = ParameterDirection.Output
insert_command.Parameters.Add(output_parameter)
insert_command.ExecuteNonQuery()
Dim reader As SqlDataReader = insert_command.ExecuteReader()
reader.Read()
id_number = reader.GetInt32(0)
reader.Close
transaction.Commit

但执行时此代码会在目标表中插入两行。从阅读器返回的id_number是第二行的ID号。

有谁知道为什么要插入两行，我该怎么办呢？（我已经检查了这个问题here，我不认为这是同一个问题，但我可以确认代码只执行一次而且表没有触发器。）

Answer 1

因为你执行了两次

insert_command.ExecuteNonQuery()
Dim reader As SqlDataReader = insert_command.ExecuteReader()

所以删除第一个并保持：

Dim reader As SqlDataReader = insert_command.ExecuteReader()

Answer 2

要获取您的ID_Number，请尝试使用ExecuteScalar：

id_number = insert_command.ExecuteScalar()

无需致电ExecuteReader或ExecuteNonQuery。

为什么这段代码会在数据库中插入两行？

2 个答案: