Duplicate Entry Prevention

John,
the most reliable way to avoid duplicates is to create unique index on this field in your table.

The syntax can be as the following (for MySQL database):

CREATE UNIQUE INDEX i_IndexName ON Table1 (Field1);

Also you can add your custom code to Add and Edit pages to look for dulicate values before the record is inserted or updated.

Then you'll be able to show more user-friendly messages.

You can insert your code before this fragment in ..._add.php file:

//  make SQL string

    $strSQL = "insert into ".AddTableWrappers($strTableName)." ";

You can use $avaluesarray to access values enterd by user. Here is the syntax:

if($avalues["`SerialNumber`"]=="'1234-abcd-cvg4-aaaa'")

Here is the place to insert your code in ..._edit.php file:

foreach($evalues as $ekey=>$value)

    $strSQL.=$ekey."=".$value.", ";

And array with values is $evalues.