Getting primary key after an insert in asp.net (visual basic)

问题:

I'm adding a record like this:

    Dim pathString As String = HttpContext.Current.Request.MapPath("Banking.mdb")     Dim odbconBanking As New OleDbConnection _              ("Provider=Microsoft.Jet.OLEDB.4.0;" & _              "Data Source=" + pathString)     Dim sql As String     sql = "INSERT INTO tblUsers ( FirstName, LastName, Address, City, Province, Zip, Phone, UserName, [Password])" & _               " VALUES ('" & firstName & "', '" & lastName & "', '" & address & _             "', '" & city & "', '" & province & "', '" & zip & "', '" & phone & "', '" & username & "', '" & password & "');"     odbconBanking.Open()     Dim cmd As New OleDbCommand(sql, odbconBanking)     cmd.ExecuteNonQuery()     odbconBanking.Close() 

The primary key is an autonumber field called UserID. So, how do I get the primary key of the record I just inserted?

Thanks.

回答1:

I believe a parameterized query would look something like this:

Dim pathString As String = HttpContext.Current.Request.MapPath("Banking.mdb") Dim odbconBanking As New OleDbConnection _      ("Provider=Microsoft.Jet.OLEDB.4.0;" & _      "Data Source=" + pathString) Dim sql As String sql = "INSERT INTO tblUsers ( FirstName, LastName, Address, City, Province, Zip, Phone, UserName, [Password])" & _       " VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?);" odbconBanking.Open() Dim cmd As New OleDbCommand(sql, odbconBanking)  //Add Params here cmd.Parameters.Add(new OdbcParameter("@FirstName", firstName)) cmd.Parameters.Add(new OdbcParameter("@LastName", lastName)) //..etc  //End add Params here  cmd.ExecuteNonQuery() Dim newcmd As New OleDbCommand("SELECT @@IDENTITY", odbconBanking) uid = newcmd.ExecuteScalar  odbconBanking.Close() 

My syntax might be a bit off as I am more accustomed to using the Sql Server library and not the Odbc library, but that should get you started.

回答2:

"SELECT @@IDENTITY" just after the insertion should work with Microsoft.Jet Provider.

回答3:

You'll want to add

;select scope_identity(); 

after your query, and run executeScalar to get the value back.

Also, on a completely unrelated note, you really should change your code to use parameterized queries so you don't get caught with SQL injection attacks, or crashes due to inproperly escaped strings concatenated into your sql statement.

回答4:

Got it. Here's how the above code looks now:

    Dim pathString As String = HttpContext.Current.Request.MapPath("Banking.mdb")     Dim odbconBanking As New OleDbConnection _              ("Provider=Microsoft.Jet.OLEDB.4.0;" & _              "Data Source=" + pathString)     Dim sql As String     sql = "INSERT INTO tblUsers ( FirstName, LastName, Address, City, Province, Zip, Phone, UserName, [Password])" & _               " VALUES ('" & firstName & "', '" & lastName & "', '" & address & _             "', '" & city & "', '" & province & "', '" & zip & "', '" & phone & "', '" & username & "', '" & password & "');"     odbconBanking.Open()     Dim cmd As New OleDbCommand(sql, odbconBanking)     cmd.ExecuteNonQuery()     Dim newcmd As New OleDbCommand("SELECT @@IDENTITY", odbconBanking)     uid = newcmd.ExecuteScalar      odbconBanking.Close() 

回答5:

The simplest way would be to generate your uniqueIdentifier value at the code level, add it to your string and send it to the server.

Dim sql As String, _     myNewUserId as variant  myNewUserId = stGuidGen    'this function will generate a new GUID value)' sql = "INSERT INTO tblUsers ( userId, LastName)" & _       " VALUES ('" & myNewUserId & "','" & LastName);" 

You can check a proposal for the stGuidGen guid generating code here.

This client-side technique is clear, clean and usefull

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