Avec SQL Server, pour calculer col4, concaténation de de col1, col2 et col3 :
IF EXISTS(SELECT '' FROM sysobjects WHERE type='FN' AND name = 'concatenons')
DROP FUNCTION concatenons ;
go
create function concatenons(@a varchar(5), @b varchar(5), @c varchar(5))
returns varchar(64)
as
begin
return @a + @b + @c
end ;
go
create table t
(
id int not null
, col1 varchar(5) not null
, col2 varchar(5) not null
, col3 varchar(5) not null
, col4 as dbo.concatenons(col1, col2, col3)
, constraint T_PK primary key (id)
) ;
insert into t (id, col1, col2, col3) values ( 1, 'ab', 'cd', 'ef') ;
insert into t (id, col1, col2, col3) values ( 2, 'dev', 'elop', 'pez') ;
select * from t ;
=>
id col1 col2 col3 col4
--- ----- ----- ----- -----------
1 ab cd ef abcdef
2 dev elop pez developpez
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