SQL Server/T-SQL/Table/Computed Column

Add value from two columns as the computed column

1>
2> CREATE TABLE T (
3>     int1 int,
4>     bit1 bit,
5>     varchar1 varchar(3),
6>     dec1 dec(5,2),
7>     cmp1 AS (int1 + bit1)
8> )
9> GO
1> INSERT T (int1, bit1) VALUES (1, 0)
2> GO
(1 rows affected)
1> INSERT T (int1, varchar1) VALUES (2, "abc")
2> GO
(1 rows affected)
1> INSERT T (int1, dec1) VALUES (3, 5.25)
2> GO
(1 rows affected)
1> INSERT T (bit1, dec1) VALUES (1, 9.75)
2> GO
(1 rows affected)
1> --Average of dec1 values
2> SELECT CAST(AVG(dec1) AS dec(5,2)) "Avg of dec1"
3> FROM T
4> WHERE dec1 IS NOT NULL
5> GO
Avg of dec1
-----------
       7.50
(1 rows affected)
1>
2>
3> drop table t
4> GO
1>

Computed columns are (by default) virtual columns not physically stored in the table

1> -- Computed columns are (by default) virtual columns not physically stored in the table.
2> SET QUOTED_IDENTIFIER ON
3> GO
1>
2> CREATE TABLE orders
3>         (id                       INT NOT NULL,
4>          price                    MONEY NOT NULL,
5>          quantity                 INT NOT NULL,
6>          orderdate                DATETIME NOT NULL,
7>          total                    AS price * quantity PERSISTED,
8>          shippeddate              AS DATEADD (DAY, 7, orderdate))
9> GO
1>
2> insert into orders (id, price, quantity, orderdate)
3>             values (1, 100, 2, "1997.10.1")
4> GO
(1 rows affected)
1>
2> select * from orders
3> GO
id          price                 quantity    orderdate               total                 shippeddate
----------- --------------------- ----------- ----------------------- --------------------- -----------------------
          1              100.0000           2 1997-10-01 00:00:00.000              200.0000 1997-10-08 00:00:00.000
(1 rows affected)
1>
2> drop table orders
3> GO