在SQL列中添加合计其他列值的值

Question

Trying to add a new column into pre-existing table with the following command:

ALTER TABLE randomquestions 
ADD Total AS R1_Number + R2_Number + R3_Number + R4_Number PERSISTED

I get this error:

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AS R1_Number + R2_Number + R3_Number + R4_Number PERSISTED' at line 2

Can anyone tell me where I went wrong with the syntax?

Answer 1

If MySQL 5.7.6+ Generated Columns :

ALTER TABLE randomquestions 
ADD Total INT AS (R1_Number + R2_Number + R3_Number + R4_Number) STORED;

Note that you may need to change datatype depending of datatype of Rx_Number .

Answer 2

Alter looks good missing parenthesis and column type.

ALTER TABLE randomquestions 
ADD Total int AS (R1_Number + R2_Number + R3_Number + R4_Number) PERSISTED

Answer 3

I tried a similar statement with the parenthesis and it worked:

use test
alter table [dbo].[tablename]
Add total2 as (price * 2) persisted 

(so I guess it's the parenthesis, it's not finding your table, or just a syntax error with the field names.)