# Creating AutoIncrement Columns

To ensure unique column values, you can set the column values to increment automatically when new rows are added to the table. To create an auto-incrementing DataColumn, set the AutoIncrement property of the column to true. The DataColumn then starts with the value defined in the AutoIncrementSeed property, and with each row added the value of the AutoIncrement column increases by the value defined in the AutoIncrementStep property of the column.

For AutoIncrement columns, we recommend that the ReadOnly property of the DataColumn be set to true.

The following example demonstrates how to create a column that starts with a value of 200 and adds incrementally in steps of 3.

Dim workColumn As DataColumn = workTable.Columns.Add( _
"CustomerID", typeof(Int32))
workColumn.AutoIncrement = true
workColumn.AutoIncrementSeed = 200
workColumn.AutoIncrementStep = 3

DataColumn workColumn = workTable.Columns.Add(
"CustomerID", typeof(Int32));
workColumn.AutoIncrement = true;
workColumn.AutoIncrementSeed = 200;
workColumn.AutoIncrementStep = 3;