More efficient way to assign values to a column in SQL Server 2008 based on other column values - sql

Question

I have a table with 5 columns like:
id value1 value2 value3 Score
1 X X X
2 X Y Z
3 Y Z Z
4 X Z X
What I want is to assign final values equal to Ys and Zs (not X) for each column like:
id value1 value2 value3 final
1 X X X 0
2 X Y Z 2
3 Y Z Z 3
4 X Z X 1
The way I am doing it is:
Update table
set final = 3
where value1 <> 'X' and value2 <> 'X' and value3 <> 'X'
Update table
set final = 2
where (value1 <> 'X' and value2 <> 'X' and value3 = 'X')
OR (value1 = 'X' and value2 <> 'X' and value3 <> 'X')
OR (value1 <> 'X' and value2 = 'X' and value3 <> 'X')
Update table
set final = 1
where (value1 <> 'X' and value2 = 'X' and value3 = 'X')
OR (value1 = 'X' and value2 <> 'X' and value3 = 'X')
OR (value1 = 'X' and value2 = 'X' and value3 <> 'X')
Update table
set final = 0
where value1 = 'X' and value2 = 'X' and value3 = 'X'
I would like to ask if there is any smarter/more efficient way rather than this? Any advice would be appreciated. Thanks!

Answer 1

Is this what you want?
Update table
set final = ((case when value1 <> 'X' then 1 else 0 end) +
(case when value2 <> 'X' then 1 else 0 end) +
(case when value3 <> 'X' then 1 else 0 end)
);
This counts the number of values that are not X.
Here is another method:
Update table
set final = len(replace(value1 + value2 + value3, 'X', '');
Note: This only works if the columns really do have values that have only one character.

Answer 2

use CASE WHEN . . .
Update table
set final = CASE WHEN value1<>'X' and value2<>'X' and value3<>'X' THEN 3
WHEN (value1<>'X' and value2<>'X' and value3='X')
OR (value1='X' and value2<>'X' and value3<>'X')
OR (value1<>'X' and value2='X' and value3<>'X') THEN 2
WHEN (value1<>'X' and value2='X' and value3='X')
OR (value1='X' and value2<>'X' and value3='X')
OR (value1='X' and value2='X' and value3<>'X') THEN 1
WHEN value1='X' and value2='X' and value3='X' THEN 0
END

Answer 3

Using Computed column. Correct me if desired output is not obtained.
CREATE TABLE GRADES (
id INT
,VALUE1 VARCHAR(10)
,VALUE2 VARCHAR(10)
,VALUE3 VARCHAR(10)
,final INT AS (
(
CASE
WHEN value1 <> 'X'
THEN 1
ELSE 0
END
) + (
CASE
WHEN value2 <> 'X'
THEN 1
ELSE 0
END
) + (
CASE
WHEN value3 <> 'X'
THEN 1
ELSE 0
END
)
)
);

Answer 4

create TRIGGER test
ON [dbo].[YourTable]
AFTER INSERT
AS
BEGIN
declare #Id int
declare #value1 nvarchar(10)
declare #value2 nvarchar(10)
declare #value3 nvarchar(10)
declare #Count int =0
select top(1) #Id=id, #value1=[m1] ,#value2=[m2],#value3=[m3] from [dbo].[Table_3] order by id DESC
if #value1='x'
begin
set #Count=#Count+1
end
if #value2='x'
begin
set #Count=#Count+1
end
if #value3='x'
begin
set #Count=#Count+1
end
update [dbo].[Table_3]
set Score=#Count
where id =#Id
END