AutoNumber In Sql 2014 is a type of data used in Microsoft Access tables to generate an automatically incremented numeric counter. It may be used to create an identity column which uniquely identifies each record in a table. Only one AutoNumber field is allowed in each table which called Counter in Access. The default AutoNumber type is a start + increment counter and start value of 1 and an increment of 1. Although in many instances such an AutoNumber In Sql 2014 field will appear as if it contains the row count, it does not. Deletion of rows from a table, for example, does not cause AutoNumber In Sql 2014 fields to be renumbered, but instead leaves holes in the numbering. Similarly, if a transaction to add a row to a table is begun but later aborted, the AutoNumber In Sql 2014 assigned for that row will not be re-used. There are reasons to choose each form, and trade-offs in doing so. The default start and increment values might reveal information about a table that it is desired not to reveal to people viewing individual table rows. For example, using an Auto Number field for a customer ID might reveal information that it is desirable not to reveal to, say, customer number 6.