为什么在我使用executenonquery时不必使用@@ identity [英] why don't I have to use @@identity when I'm using executenonquery
问题描述
Hi
表Film具有ID和Film列.列ID是一个主键和一个自动编号.
当我使用此代码时，连接的版本可以正常工作.
Hi
The table Film has columns ID and Film. The column ID is a primarykey and an autonumber.
When I'm using this code, the connected version, it works fine.
strSQL = 插入胶片(胶片)值(?)"
strSQL = "Insert into Film (Film) values(?)"
cmorder = 新 OleDb.OleDbCommand(strSQL，conn)
cmorder = New OleDb.OleDbCommand(strSQL, conn)
Me .dFilmAdpt.InsertCommand = cmorder
Me.dFilmAdpt.InsertCommand = cmorder
Me .dFilmAdpt.InsertCommand .Parameters.Add( "Film" ，OleDbType.LongVarChar)
Me.dFilmAdpt.InsertCommand.Parameters.Add("Film", OleDbType.LongVarChar)
conn.Open()
conn.Open()
dFilmAdpt .InsertCommand.Parameters(table).Value = cbo.Text
dFilmAdpt .InsertCommand.ExecuteNonQuery()
dFilmAdpt.InsertCommand.Parameters(table).Value = cbo.Text
dFilmAdpt.InsertCommand.ExecuteNonQuery()
conn.Close()
但是当我使用断开连接的版本时，它不起作用.我已经知道我可以使用OnRowUpdated和@@ identity，但是我不明白为什么在我使用executenonquery时它起作用，而在我不使用时就不起作用.与数据库的连接或断开连接有任何关系.
da.Fill(ds， 电影" )
conn.Close()
But when I'm using the disconnected version it doesn't work. I have seen that I can use OnRowUpdated and @@identity, but I don't undertstand why it works when I'm using executenonquery and not when I don't. Has it anything with connection or disconnection to the database.
da.Fill(ds, "Film")
dt = ds.Tables( 电影" )
dt = ds.Tables("Film")
Dim insCommand 为 新建 OleDbCommand( "插入Film(Film)values(?)" ，conn)
Dim insCommand As New OleDbCommand("insert into Film(Film)values(?)", conn)
暗淡 为 新建 OleDbParameter
Dim par As New OleDbParameter
par.ParameterName = 电影"
par.ParameterName = "Film"
par.SourceColumn = " ;电影"
par.SourceColumn = "Film"
insCommand.Parameters.Add(par)
insCommand.Parameters.Add(par)
dFilmAdpt.InsertCommand = insCommand
dFilmAdpt.InsertCommand = insCommand
Dim newRow = dt. NewRow
Dim newRow = dt.NewRow
newRow( 电影" )= cbo.Text
newRow("Film") = cbo.Text
dt.Rows.Add(newRow)
dFilmAdpt.Update(ds)
dt.Rows.Add(newRow)
dFilmAdpt.Update(ds)
请解释，并请准确解释
Fia
推荐答案
原因是数据集使用其自身的机制在内存中临时创建行，并且在插入db时需要使用自动生成的数字.
Still Around?
The reason is that the dataset uses its own mechanism to temporarily create rows in memory and when inserting in db, it needs to use the autogenerated numbers.
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