How to run query for this - tsql

Question

MyTable has four columns.
Condition1 | Condition2 | CondEquation | EquationResult
---------------------------------------------------------
1 | 0 | C1 & C2 | 0
1 | 1 | C1 & C2 | 1
EquationResult data is select C1 & C2. It is evaluated expression of CondEquation.
How to update the 4th column using SQL statements.
Is there anyway I can write function for this?
SQL Server 2008 R2
Thank you,
Smith

Answer 1

Sure. But I can only deliver you a solution that is based on a cursor, I hope that's not a problem.
use testing
-- create table test_01 (c1 int, c2 int, ce nvarchar(100), result int)
insert into test_01 (c1, c2, ce) values (1, 0, 'c1 & c2')
insert into test_01 (c1, c2, ce) values (1, 1, 'c1 & c2')
insert into test_01 (c1, c2, ce) values (7, 3, 'c1 & c2')
insert into test_01 (c1, c2, ce) values (2, 4, 'c1 | c2')
declare #eq nvarchar(100)
declare #sql_statement nvarchar(500)
declare c cursor for select ce from test_01
open c
fetch next from c into #eq
while ##fetch_status = 0
begin
-- update test_01 set result = (c1 & c2) where current of c
set #sql_statement = 'update test_01 set result = (' + #eq + ') where current of c'
exec sp_executesql #sql_statement
fetch next from c into #eq
end
close c
deallocate c
select * from test_01
This gives the following results:
c1 c2 ce result
1 0 c1 & c2 0
1 1 c1 & c2 1
7 3 c1 & c2 3
2 4 c1 | c2 6

Answer 2

Here is a script that will show the cEquationResult even when data change in the table, it can only handle the bit operators & and |
Table to represent your table:
create table t_test(condition1 bit, condition2 bit, condition3 bit, CondEquation varchar(20))
insert t_test values(1,0, 0, 'c1&c2|c3')
insert t_test values(1,1, 1, 'c1&c2 | c3')
go
Function to calculate the calculated bit. Yes it IS a mean one:
create function f_t(#condition1 bit, #condition2 bit, #condition3 bit, #CondEquation varchar(10))
returns bit
as
begin
declare #result bit
;with a as
(
select replace(replace(replace(replace(#CondEquation, 'c1',#condition1), 'c2',#condition2), 'c3',#condition3), ' ','') n
),
b as
(
select n, 1 rn from a
union all
select stuff(n, patindex('%&%', n) - 1, 3 , case when substring(n, patindex('%&%', n) - 1, 3) like '%0%' then 0 else 1 end), rn+1
from b
where patindex('%&%', n)> 0
), c as
(
select n from (
select n, row_number() over (order by rn desc) rn2 from b
) a where rn2 = 1
), d as
(
select n, 1 rn from c
union all
select stuff(n, patindex('%|%', n) - 1, 3 , case when substring(n, patindex('%|%', n) - 1, 3) like '%1%' then 1 else 0 end), rn+1
from d
where patindex('%|%', n)> 0
), e as
(
select n from (
select n, row_number() over (order by rn desc) rn2 from d
) a where rn2 = 1
)
select #result=n from e
return #result
end
go
adding the extra field to show the calculated bit
ALTER TABLE t_test ADD cEquationResult AS
dbo.f_t(condition1, condition2, condition3, CondEquation)
Testing the scripts:
select * from t_test