#TABLEPLUS SEE FIELD RESTRICTIONS CODE#
When the code in Listing 14 is run, the results in Report 4 are created. The first sample table is named Sample and can be created using the script in Listing 1. To show you how this example works, first create a couple of sample tables. Replacing an identity column in an existing table using a column populated with a sequence number requires a few steps. Option 1: Modify existing table to use sequence number This article explores both of these options and provides examples of how these options can be used to replace an identity column with a sequence number. Another option is to create another table that uses a sequence object and then use the ALTER TABLE SWITCH operation. One option is to modify your table to add a sequence number column and then delete the identity column. This article demonstrates two different options. If you decide to change an identity column to a sequence number, there is more than one way to accomplish the conversion. Need to allow a sequence number column to be nullable.Ĭonverting identity column to sequence number.Need to store a sequence number in a data type other than numeric.Need to be able to change the specification for the sequence number over time.Need to retrieve multiple sequence numbers at the same time without gaps.Need to cycle through a series of numbers, over and over again.Need to share sequence numbers across tables.Need to know the sequence number prior to inserting a record.Here are a few of the reasons why you might want to change an identity column to a sequence number: When this occurs, you might find the sequence number object more flexible. Why replace the identity columnĪn Identity column might not be flexible enough to support all business requirements an application might need around a series of identity values. This article demonstrates two options for replacing an identity column with a sequence number. Over time, you might find that the additional benefits of a sequence number have you wanting to replace an identity column with a sequence number. A sequence object generates sequence numbers based on starting and increment values, similar to an identity column, but it has additional features. Microsoft introduced the sequence number objects starting with SQL Server 2012.
#TABLEPLUS SEE FIELD RESTRICTIONS HOW TO#
How to replace an identity column with a sequence number.
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