I have created a working SQL query but it's ugly. I am using the statement:
CASE WHEN p.Guests is null THEN 0 ELSE p.Guests
About 10 times in some calculations being done in the query and I am wondering if it is possible to do something like:
variable = CASE WHEN p.Guests is null THEN 0 ELSE p.Guests
and then instead of 123 * (CASE WHEN p.Guests is null THEN 0 ELSE p.Guests)
I could do 123 * variable. p.Guests is the number of guests attending an event and it varies based on each row in the query.
So my question is: is there a way to make a variable like this in SQL?
No need for a long-winded case statement when there's
ISNULL(p.Guests, 0)
http://msdn.microsoft.com/en-us/library/ms184325.aspx
You can use ISNULL:
select 123 * ISNULL(p.Guests,0) FROM ...
The ISNULL function will return the first parameter, unless it is null in which case it will return the second parameter.
Related
I need the WHERE clause to change what column it is evaluating when NULL is encountered. For instance I'm trying to do something like this:
SELECT *
FROM customer c
WHERE CASE WHEN c.cust_id_1(#variable) IS NOT NULL THEN c.cust_id_1 = #variable
ELSE CASE WHEN c.cust_id_2(#variable) IS NOT NULL THEN c.cust_id_2 = #variable
ELSE c.cust_id_3 = #variable
Is something like this possible? One of the 3 cust_id's will not be NULL.
That seems like less than optimal table design, but isn't a simple COALESCE where you're after?
WHERE #variable = COALESCE(cust_id_1, cust_id_2, cust_id_3);
You don't need a CASE expression for this, you just need logical operators
SELECT *
FROM customer c
WHERE
(c.cust_id_1 IS NOT NULL AND c.cust_id_1 = #variable)
OR
(c.cust_id_2 IS NOT NULL AND c.cust_id_2 = #variable)
OR
(c.cust_id_3 IS NOT NULL AND c.cust_id_3 = #variable)
Hi can any one say me how to write query in sql server management studio for statement =>if(isnull("GROSS_SF")=1 or "GROSS_SF"=0,0,"GROSS_SALES"/"GROSS_SF")
by using case statement :
CASE
WHEN ("GROSS_SF"=1 or "GROSS_SF"=0) isnull then 0
else "GROSS_SALES"/"GROSS_SF"
end/* i am getting error if i write it like this */
thanks in advance
If you want to avoid a divide by zero, while at the same time also handling NULL, then you may try the following logic:
CASE WHEN COALESCE(GROSS_SF, 0) = 0
THEN 0
ELSE GROSS_SALES / GROSS_SF END AS output
To be clear, the above logic would return a zero value should either the GROSS_SF be zero or NULL.
I think what are you looking for is IFNULL, look here https://www.w3schools.com/sql/sql_isnull.asp
You are close. You can do:
(CASE WHEN "GROSS_SF" IS NULL OR "GROSS_SF" = 0 THEN 0
ELSE "GROSS_SALES" / "GROSS_SF"
END)
In SQL, divide by zero errors are often avoided using NULLIF():
"GROSS_SALES" / NULLIF("GROSS_SF", 0)
However, that returns NULL rather than 0. If you really want zero:
COALESCE("GROSS_SALES" / NULLIF("GROSS_SF", 0), 0)
This is a bit shorter to write and almost equivalent to your version (this returns 0 if "GROSS_SALES" is NULL, which your version does not).
You can use NULLIF() to prevent arithmetic divide by zero errors :
select . . . ,
GROSS_SALES / nullif(GROSS_SF, 0)
from table t;
However, this would return null instead of error, if you want to display 0 instead then you need to use isnull() (MS SQL Specific) or coalesce() (SQL Standard).
So, you can express it :
select . . . ,
isnull(GROSS_SALES / nullif(GROSS_SF, 0), 0)
from table t;
I have condition in datastage which verifies 30 columns as not null and assigning value as '0' if anyone of the field is null like below,
isnull(columnA) or isNull(coloumnB) or isnull(columnC) or isNull(coloumnD) then 0 else 1.
we have option to use case statement in hive to set values, however we have to give use CASE statement per column like below,
select
case when (columnA is NULL) then 0
case when (columnB is NULL) then 0
case when (columnC is NULL) then 0
.
.
.
else 1
end as iValidColumn
From tablea
What i am looking?
Trying to look for option where we can validate all the 30 columns in condition for null validation.
In C, when you compared true/false value to 1/0, it worked very well.
I would want the similar possibility with SQL Server - when I have a bit column, I would like to compare myBitField = 'y' / myBitField = 'n'
Is there anything I can do about that? Maybe change some SQL interpreter settings or something?
Example of what I would like to do:
select * from
(
select CAST(1 AS BIT) as result
) as main
where main.result = 'y'
Currently, it throws an error, and I would like it to return 1/true/'y', whatever, but I would like it to be able to make that comparison.
I suppose you want to do it for some yes/no thing. But this is generally a wrong concept, your application which is accessing the SQL Server should interpret y as a 1 and n as a 0 and afterwards set the correct parameters for the query. You should not (actually I'm temped to write "must not") do this in SQL Server, that's what you have a business logic for.
As others have said, BIT and CHAR / VARCHAR are entirely different datatypes. But if you want to cast them during the select, you can use CASE expression like so:
-- Reading string as BIT
SELECT CAST(CASE RESULT WHEN 'Y' THEN 1 WHEN 'N' THEN 0 ELSE NULL END AS BIT) RESULT
-- Reading BIT as string
SELECT CAST(CASE RESULT WHEN 1 THEN 'Y' WHEN 0 THEN 'N' ELSE NULL END AS CHAR(1)) RESULT
And that's about as far as your options go here, far as I can understand. :)
I have seen similar questions asked elsewhere on this site, but more in the context of optimization.
I am having an issue with the order of execution of the conditions in a WHERE clause. I have a field which stores codes, most of which are numeric but some of which contain non-numeric characters. I need to do some operations on the numeric codes which will cause errors if attempted on non-numeric strings. I am trying to do something like
WHERE isnumeric(code) = 1
AND CAST(code AS integer) % 2 = 1
Is there any way to make sure that the isnumeric() executes first? If it doesn't, I get an error...
Thanks in advance!
The only place order of evaluation is guaranteed is CASE
WHERE
CASE WHEN isnumeric(code) = 1
THEN CAST(code AS integer) % 2
END = 1
Also just because it passes the isnumeric test doesn't guarantee that it will successfully cast to an integer.
SELECT ISNUMERIC('$') /*Returns 1*/
SELECT CAST('$' AS INTEGER) /*Fails*/
Depending upon your needs you may find these alternatives preferable.
Why not simply do it using LIKE?:
Where Code Not Like '%[^0-9]%'
Btw, either using my solution or using IsNumeric, there are some edge cases which might lead one to using a UDF such as 1,234,567 where IsNumeric will return 1 but Cast will throw an exception.
Why not use a CASE statement to say something like:
WHERE
CASE WHEN isnumeric(code) = 1
THEN CAST(code AS int) % 2 = 1
ELSE /* What ever else if not numeric */ END
You could do it in a case statement in the select clause, then limit by the value in an outer select
select * from (
select
case when isNum = 1 then CAST(code AS integer) % 2 else 0 end as castVal
from (
select
Case when isnumeric(code) = 1 then 1 else 0 end as isNum
from table) t
) t2
where castval = 1