I've got the below expression and even though I thought I was handling 'NaN' values properly I still get them when I click preview. Does anybody know how to change it, so that NaN values get replaced with 0. Thanks.
=0 + Sum(IIF(IsNothing(Fields!value.Value) = True, 0, Fields!value.Value)) / IIF(Information.IsNothing(Fields!value.Value) = True, 0, CountDistinct(Fields!Introducer.Value))
NaN means that the SSRS couldn't calculate the value. Looking at your expression, looks like it's because you could very easily end up with a divide by 0. If I understand your expression correct, I would do:
IIf(IsNothing(Fields!value.Value) OR (CountDistinct(Fields!Introducer.Value) = 0), 0, Fields!value.Value / CountDistinct(Fields!Introducer.Value))
When you run the following query in SQL Management studio the result will be 1.
SELECT
CASE WHEN '-' = 0 THEN
1
ELSE
0
END
That scares me a bit, because I have to check for 0 value a numerous number of times and it seems it is vulnerable for being equal to value '-'.
You're looking at it the wrong way around.
'-' is a string, so it will get implicitly casted to an integer value when comparing it with an integer:
select cast('-' as int) -- outputs 0
To make sure that you are actually comparing a value to the string '0', make your comparison like this instead:
select case when '-' = '0' then 1 else 0 end
In general, you're asking for trouble when you're comparing values of different data types, since implicit conversions happen behind the scene - so avoid it at all costs.
If y is of integer type, then the expressions:
3*(y-8)/9
and
(y-8)/9*3
Will yield different result always or is it possible for them to yield same result?
What does it depend on?
Explanation with an example will be helpful.
May yield different or same result, it is depend on 'y' value. The operations will be carried from left to right.
Ex: for y=11:
3*(y-8)/9: 1 (y-8)/9*3: 0
for y = 10
3*(y-8)/9: 0 (y-8)/9*3: 0
This is the DFA i have drawn-
Is it correct?
I am confused because q4 state has 2 different transitions for same input symbol which violates the rule of DFA, but I can't think of any other solution.
Your DFA is not correct.
your DFA is completely wrong so I don't comment
DFA for RE:
0(1 + 0)*0 + 1(1 + 0)*1
Language Description: if string start with 0 it should end with 0 or if string start with 1 it should end with 1. hence two final states (state-5, state-4).
state-4 : accepts 1(1 + 0)*1
state-5 : accepts 0(1 + 0)*0
state-1 : start state.
DFA:
EDIT :
+ Operator in Regular Expression
(0 + 1)* = (1 + 0)* that is any string consist of 1s and 0s, including Null string ^.
Here + means Union if it appear between two RE: and A U B = B U A (similarly)=> (0 + 1) = (0 + 1) .
meaning of plus + depends on syntax it appears in: If expression is a+ (+ is superscripted) this means one of more as, and If a+b then + means Union operation either a or b.
a+ : { a, aa, aaa, aaa.....} that is any number of a string in language with length > 1.
I think you should start with 0 first
0(1 + 0)*0 + 1(1 + 0)*1
I would like to use AND/OR between the conditions in a stored procedure, and the decision is dependent on the parameter value whether it was 0 (AND) or 1 (OR)
Can anyone help me with this please, i guess this is an easy thing to do but i can't seem to figure it out. Thanks
The easiest way (on first glance) would be to concatenate the query string using dynamic SQL, but dynamic SQL has its issues.
See The Curse and Blessings of Dynamic SQL for an in-depth explanation.
So I would try to avoid dynamic SQL, which is no big deal if your queries are not too complex.
The easiest way is just to fire two different queries depending on the parameter value:
CREATE PROCEDURE spTest
#AndOr bit
AS
BEGIN
if #AndOr = 0 begin
select * from YourTable where foo = 1 and bar = 2
end
else begin
select * from YourTable where foo = 1 or bar = 2
end
END
This is of course an example with a very simple query.
If you have lots of queries, or if your queries are very complex, this might not be the best solution because it forces you to duplicate all queries...but as always, it depends :-)
You can implement your logic on a CASE statement. Something like this:
CREATE PROCEDURE dbo.MySP #OrAnd BIT
AS
BEGIN
SELECT *
FROM MyTable
WHERE CASE WHEN Condition1 AND Condition2 AND #OrAnd = 0 THEN 1
WHEN (Condition1 OR Condition2) AND #OrAnd = 1 THEN 1 ELSE 0 END = 1
END
If you convert the simple conditions' boolean results into numeric ones (0 or 1), you will be able to use your parameter in the following way:
(
(CASE WHEN condition1 THEN 1 ELSE 0 END ^ #AndOr)
&
(CASE WHEN condition2 THEN 1 ELSE 0 END ^ #AndOr)
) ^ #AndOr = 1
Here #AndOr is your parameter, ^ is the Transact-SQL bitwise exclusive OR operator, & stands for the bitwise AND in Transact-SQL, and the CASE expressions are used to convert the boolean results into 0 or 1.
If #AndOr = 0 (which means we want AND between the conditions), the above expression effectively boils down to this:
case1 & case2 = 1
because X XOR 0 yields X and so neither individual values of case1 and case2 nor the entire result of the & operator are not affected by the ^ operators. So, when #AndOr is 0, the result of the original expression would be equivalent to the result of condition1 AND condition2.
Now, if #AndOr = 1 (i.e. OR), then every ^ operator in the expression returns the inverted value of its left operand, in other words, negates the left operand, since 1 XOR 1 = 0 and 0 XOR 1 = 1. Therefore, the original expression would essentially be equivalent to the following:
¬ (¬ case1 & ¬ case2) = 1
where ¬ means negation. Or, converting it back to the booleans, it would be this:
NOT (NOT condition1 AND NOT condition2)
According to one of De Morgan's laws,
(NOT A) AND (NOT B) = NOT (A OR B)
Applying it to the above condition, we get:
NOT (NOT condition1 AND NOT condition2) = NOT (NOT (condition1 OR condition2)) =
= condition1 OR condition2
So, when #AndOr is 1, the expression given in the beginning of my answer is equivalent to condition1 OR condition2. Thus, it works like expected based on the value of #AndOr.
Having the input parameter you can use a IF clause to make different selects.
If input parameter = 0 make the AND conditions, otherwise make the OR conditions.
I can't see any particular elegant way to do it. So here's the straightforward approach
create function myfun (#parm1 int, #parm2 int, #andor int) returns int
begin
if (#andor = 0 AND #parm1 = 99 AND #parm2 = 99) return 1
else if (#andor = 1 AND (#parm1 = 99 OR #parm2 = 99)) return 1
return 0
end
go
select dbo.myfun(99,98,0) -- AND condition should return 0
select dbo.myfun(99,98,1) -- OR condition should return 1
select dbo.myfun(98,98,0) -- AND condition should return 0
select dbo.myfun(98,98,1) -- OR condition shoujld return 0