How would you get the last Primary Key/Auto Increment value in a table using OleDb?
I need to get this value so I can create a folder for a record before it is added so that files can be copied to the folder when it is added.
Any idea? I have tried as following.
@@Identity
'Need to insert a record first and I can't do that without copying the files first SELECT SCOPE_IDENTITY()
'Doesn't work with OleDb
This is the error message I get:
我认为这可能有效:
SELECT MAX(ID) FROM MyTable
you can do it like this because of The Jet 4.0 provider supports @@Identity
, Reference
Dim query As String = "Insert Into Categories (CategoryName) Values (?)"
Dim query2 As String = "Select @@Identity"
Dim ID As Integer
Dim connect As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|Northwind.mdb"
Using conn As New OleDbConnection(connect)
Using cmd As New OleDbCommand(query, conn)
cmd.Parameters.AddWithValue("", Category.Text)
conn.Open()
cmd.ExecuteNonQuery()
cmd.CommandText = query2
ID = cmd.ExecuteScalar()
End Using
End Using
Try this
Select IDENT_CURRENT('TableName')
It Will retrun Last ID(If it's Auto increment) of your Table
**c#**
string query = "Insert Into Categories (CategoryName) Values (?)";
string query2 = "Select @@Identity";
int ID;
string connect = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|Northwind.mdb";
using (OleDbConnection conn = new OleDbConnection(connect))
{
using (OleDbCommand cmd = new OleDbCommand(query, conn))
{
cmd.Parameters.AddWithValue("", Category.Text);
conn.Open();
cmd.ExecuteNonQuery();
cmd.CommandText = query2;
ID = (int)cmd.ExecuteScalar();
}
}
**VB**
Dim query As String = "Insert Into Categories (CategoryName) Values (?)"
Dim query2 As String = "Select @@Identity"
Dim ID As Integer
Dim connect As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|Northwind.mdb"
Using conn As New OleDbConnection(connect)
Using cmd As New OleDbCommand(query, conn)
cmd.Parameters.AddWithValue("", Category.Text)
conn.Open()
cmd.ExecuteNonQuery()
cmd.CommandText = query2
ID = cmd.ExecuteScalar()
End Using
End Using
您可以先尝试检查是否为 NULL:
Select if(IsNull(Max(ColName)),1,Max(ColName) + 1 ) From YourTable
try this (vb.net)
'''
Dim lastrecord As Integer
Dim command As New SqlCommand("Select IDENT_CURRENT('tbluom')+1", conn)
command.ExecuteNonQuery()
Dim dt As New DataTable()
Dim da As New SqlDataAdapter(command)
lastrecord = command.ExecuteScalar()
txt_uomid.Text = lastrecord
MsgBox(lastrecord)
Dim encode As String = txt_uomid.Text '"99999"
Dim encint As Integer = Integer.Parse(encode) '+ 1
encode = "00" & "-" & encint.ToString("00000").Substring(1, 4)
MsgBox(encode)
''''
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