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Old November 18th, 2007, 02:56 PM
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Default Checking for duplicate entry in Database


I am trying to stop a duplication of a order being processed by querying the database to see if the duplicate order number exists and then use an IF statement to provide a message to stop it being duplicated.

I am able to open the connection to the database as follows but not sure on how to query it to find out if this particular order number exists to be able to then include the IF statement: -

DBConnection = New OleDbConnection ( _
  ConfigurationSettings.AppSettings("ConnectionStrin g"))
SQLString = "SELECT * FROM ShopBasket INNER JOIN Products " & _
 "ON ShopBasket.ItemNumber = Products.ItemNumber " & _
 "WHERE OrderNumber = '" & Session("OrderNumber") & "' " & _
 "ORDER BY ShopBasket.ItemNumber"
DBCommand = New OleDbCommand(SQLString, DBConnection)

Please can anyone assist me with this problem.

Many Thanks

Old November 18th, 2007, 06:08 PM
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You can use the SQL syntax

if exists
  <sql query>
<do something>
<do something else>

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