Validating columns

The result of most expressions is considered nullable even if only nonnullable columns are present, because possible underflows or overflows also produce NULL results.Use the COLUMNPROPERTY function with the Allows Null property to investigate the nullability of any computed column in a table.If the PRIMARY KEY or UNIQUE constraint creates a clustered index, the data pages for the table are stored in the same filegroup as the index.If CLUSTERED is specified or the constraint otherwise creates a clustered index, and a Note In this context, default is not a keyword.

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TEXTIMAGE_ON Indicates that the text, ntext, image, xml, varchar(max), nvarchar(max), varbinary(max), and CLR user-defined type columns (including geometry and geography) are stored on the specified filegroup.PERSISTED Specifies that the SQL Server Database Engine will physically store the computed values in the table, and update the values when any other columns on which the computed column depends are updated.Marking a computed column as PERSISTED lets you create an index on a computed column that is deterministic, but not precise.Note After you create a partitioned table, consider setting the LOCK_ESCALATION option for the table to AUTO.This can improve concurrency by enabling locks to escalate to partition (Ho BT) level instead of the table.