The expression can be a noncomputed column name, constant, function, variable, and any combination of these connected by one or more operators.
The expression cannot be a subquery or contain alias data types.
Computed columns can be used in select lists, WHERE clauses, ORDER BY clauses, or any other locations in which regular expressions can be used, with the following exceptions: Based on the expressions that are used, the nullability of computed columns is determined automatically by the Database Engine.
The result of most expressions is considered nullable even if only nonnullable columns are present, because possible underflows or overflows also produce NULL results.
Department_History, DATA_CONSISTENCY_CHECK = ON ) ); CREATE SCHEMA History GO CREATE TABLE dbo.
Department ( Department Number char(10) NOT NULL PRIMARY KEY CLUSTERED, Department Name varchar(50) NOT NULL, Manager ID int NULL, Parent Department Number char(10) NULL, Sys Start Time datetime2 GENERATED ALWAYS AS ROW START HIDDEN NOT NULL, Sys End Time datetime2 GENERATED ALWAYS AS ROW END HIDDEN NOT NULL, PERIOD FOR SYSTEM_TIME (Sys Start Time, Sys End Time) ) WITH ( MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA, SYSTEM_VERSIONING = ON ( HISTORY_TABLE = History.
The column is computed from an expression that uses other columns in the same table.
For example, a computed column can have the definition: cost AS price * qty.
An expression that is nullable can be turned into a nonnullable one by specifying ISNULL with the constant, where the constant is a nonnull value substituted for any NULL result.Marking a computed column as PERSISTED lets you create an index on a computed column that is deterministic, but not precise.For more information, see Indexes on Computed Columns.If CLUSTERED is specified or the constraint otherwise creates a clustered index, and a Note In this context, default is not a keyword.It is an identifier for the default filegroup and must be delimited, as in ON "default" or ON [default].