I have a long stored procedure with cross joins and left joins. I have several parameters in this table. On the last two left joins, I want to add a conditional where clause based on a parameter.
I will call this parameter #NonCAT which basically category code. The where clause that I am trying to implement just weeds out the non-category codes. The codes for the non-category codes are as follows:
CATCOD IN ('0', '114', '214', '314', '414', '614')
So any of those numbers in the CATCOD column are considered noncat codes.
Otherwise, if they are included, like if they are not in a where clause, they are considered cat codes. so here is my where clause in the last two left joins:
AND CASE
WHEN il.CATCOD IN ('0', '114', '214', '314', '414', '614')
THEN 'NonCAT'
ELSE 'CAT'
END = #NonCAT
This works just fine if I am trying to extract the category codes the #NonCAT variable is just a varchar(20) and it's set to 'NonCAT' as its value for now for the sake of testing. With the where clause in place, I am going to extract the non-cat codes.
I want a conditional statement, say if the variable #NonCAT = 'CAT', I want to omit that where clause. How do I go about doing this? I have tried various case statements and it's harder than it sounds. Thanks so much for the help.
Edit: I tried using iff statement in a where clause for example,
AND (IF #NonCAT = 'NonCAT'
BEGIN
CASE
WHEN il.CATCOD IN ('0', '114', '214', '314', '414', '614')
THEN 'NonCAT'
ELSE 'CAT'
END = #NonCAT
END)
Seems like that doesn't work. I can use an IF statement at the very begging of the code as a flag but that doesn't seem very efficient because I would have to rewrite the whole thing without a where clause if that makes sense.
You mean something like this?
WHERE ( ( #nonCAT = 'nonCAT' AND il.CATCOD IN ('0', '114', '214', '314', '414', '614') )
OR ( (ISNULL(#nonCAT,'') <> 'nonCAT' ))
Related
I wasn't really sure of the best wording for the question but here is my dilemma:
I am passing a value to a sql query as #district. This value may be the exact district but it also has the possibility of being a value that should create a set of multiple districts. So if I pass 002 I want the WHERE clause to say I.Offense_Tract = #district. If I pass Other I want the WHERE clause to say I.Offense_Tract in (). What I am trying to do is something like:
AND
CASE
WHEN #district = "Other" THEN I.Offense_Tract in ('BAR','COL','GER','MEM','MIL','JAIL','JAILEAST','SCCC','1USD','2USD')
ELSE I.Offense_Tract = #district
END
But this doesn't work. The problem, restated, is if the value passed is anything other than Other, I just want it to be =. If Other is passed, I want it to be IN.
You don't need the CASE expression.
You can apply this logic with operators AND and OR:
AND (
(#district = 'Other' AND I.Offense_Tract IN ('BAR','COL','GER','MEM','MIL','JAIL','JAILEAST','SCCC','1USD','2USD'))
OR
(#district <> 'Other' AND I.Offense_Tract = #district)
)
Note that, in databases like MySql, Postgresql and SQLite, your code would work as it is.
I am trying to run this query where IN clause uses CASE to choose values between two cases.
The issue is with the hard coded value('aaa','bbb'). I cannot add multiple values inside THEN so it act as regular IN values. The hard code values will be dynamic as I will pass a variable for it.
select kdo.field0
from tb1 data1 inner join tb2 kdo
on kdo.field1 = 'xxx'
and kdo.field2::DATE >='2017-08-01'::DATE
and kdo.field0
in (case when 'asd'!='' then 'aaa','bbb'
else tb2.field0 end);
Also, I used a sub-query select inside THEN to get specific hard code values but it is also of no avail. Using single hard-coded value obviously works as usual.
Move your CASE outside IN:
select kdo.field0
from tb1 data1 inner join tb2 kdo
on kdo.field1 = 'xxx'
and kdo.field2::DATE >='2017-08-01'::DATE
and case when 'asd'!='' then kdo.field0 in ('aaa','bbb')
else kdo.field0=tb2.field0 end;
however I'm not sure what do you mean by 'asd'!='' since 'asd' is a string and this will always return true
also, else tb2.field0 end); part in your statement is not an array option, it's a column name so I assume this just translates to kdo.field0=tb2.field0 because if the previous case option is false you want to check if kdo.field0 is equal to any of values in tb2.field0 which is basically a join condition
This should be a simple one, but I have not found any solution:
The normal way is using an alias like this:
CASE WHEN ac_code='T' THEN 'time' ELSE 'purchase' END as alias
When using alias in conjunction with UNION ALL this causes problem because the alias is not treated the same way as the other columns.
Using an alias to assign the value is not working. It is still treated as alias, though it has the column name.
CASE WHEN ac_code='T' THEN 'time' ELSE 'purchase' END as ac_subject
I want to assign a value to a column based on a condition.
CASE WHEN ac_code='T' THEN ac_subject ='time' ELSE ac_subject='purchase' END
Now I get the error message
UNION types character varying and boolean cannot be matched
How can I assign a value to a column in a case statement without using an alias in the column (shared by other columns in UNION)?
Here is the whole (simplified) query:
SELECT hr_id,
CASE WHEN hr_subject='' THEN code_name ELSE hr_subject END
FROM hr
LEFT JOIN code ON code_id=hr_code
WHERE hr_job='123'
UNION ALL
SELECT po_id,
CASE WHEN po_subject='' THEN code_name ELSE po_subject END
FROM po
LEFT JOIN code ON code_id=po_code
WHERE po_job='123'
UNION ALL
SELECT ac_id,
CASE WHEN ac_code='T' THEN ac_subject='time' ELSE ac_subject='purchase' END
FROM ac
WHERE ac_job='123'
There is no alias in your presented query. You are confusing terms. This would be a column alias:
CASE WHEN hr_subject='' THEN code_name ELSE hr_subject END AS ac_subject
In a UNION query, the number of columns, column names and data types in the returned set are determined by the first row. All appended rows have to match the row type. Column names in appended rows (including aliases) are just noise and ignored. Maybe useful for documentation, nothing else.
The = operator does not assign anything in a SELECT query. It's the equality operator that returns a boolean value. TRUE if both operands are equal, etc. This returns a boolean value: ac_subject='time' Hence your error message:
UNION types character varying and boolean cannot be matched
The only way to "assign" a value to a particular output column in this query is to include it at the right position in the SELECT list.
The information in the question is incomplete, but I suspect you are also confusing the empty string ('') with the NULL value. A distinction that you need to understand before doing anything else with relational databases. Maybe start here. In this case you would rather use COALESCE to provide a default for NULL values:
SELECT hr_id, COALESCE(hr_subject, code_name) AS ac_subject
FROM hr
LEFT JOIN code ON code_id=hr_code
WHERE hr_job = '123'
UNION ALL
SELECT po_id, COALESCE(po_subject, code_name)
FROM po
LEFT JOIN code ON code_id=po_code
WHERE po_job = '123'
UNION ALL
SELECT ac_id, CASE WHEN ac_code = 'T' THEN 'time'::varchar ELSE 'purchase' END
FROM ac
WHERE ac_job = '123'
Just an educated guess, assuming type varchar. You should have added table qualification to column names to clarify their origin. Or table definitions to clarify everything.
The CASE expression is supposed to return a value, e.g. 'time'.
Your value is another expression subject ='time' which is a boolean (true or false).
Is this on purpose? Does the other query you glue with UNION have a boolean in that place, too? Probably not, and this is what the DBMS complains about.
I found the problem.
CASE WHEN hr_subject=’’ THEN code_name ELSE hr_subject END
The columns code_name and hr_subject was different length. This caused the unpredictable result. I think that aliases can work now.
Thank you for your support.
I'm writing my first SQL CASE statement and I have done some research on them. Obviously the actual practice is going to be a little different than what I read because of context and things of that nature. I understand HOW they work. I am just having trouble forming mine correctly. Below is my draft of the SQL statement where I am trying to return two values (Either a code value from version A and it's title or a code value from version B and its title). I've been told that you can't return two values in one CASE statment, but I can't figure out how to rewrite this SQL statement to give me all the values that I need. Is there a way to use a CASE within a CASE (as in a CASE statement for each column)?
P.S. When pasting the code I removed the aliases just to make it more concise for the post
SELECT
CASE
WHEN codeVersion = A THEN ACode, Title
ELSE BCode, Title
END
FROM Code.CodeRef
WHERE ACode=#useCode OR BCode=#useCode
A case statement can only return one value. You can easily write what you want as:
SELECT (CASE WHEN codeVersion = 'A' THEN ACode
ELSE BCode
END) as Code, Title
FROM Code.CodeRef
WHERE #useCode in (ACode, BCode);
A case statement can only return a single column. In your scenario, that's all that is needed, as title is used in either outcome:
SELECT
CASE
WHEN codeVersion = "A" THEN ACode,
ELSE BCode
END as Code,
Title
FROM Code.CodeRef
WHERE ACode=#useCode OR BCode=#useCode
If you actually did need to apply the case logic to more than one column, then you'd need to repeat it.
Here is what I normally use:
SELECT
CASE
WHEN codeVersion = "A" THEN 'ACode'
WHEN codeVersion = "B" THEN 'BCode'
ELSE 'Invalid Version'
END as 'Version',
Title
FROM Code.CodeRef
WHERE
CASE
WHEN codeVersion = "A" THEN ACode
WHEN codeVersion = "B" THEN BCode
ELSE 'Invalid Version'
END = 'Acode'
my suggestion uses an alias. note on aliases: unfortunately you can't use the alias 'Version' in a where/group by clause. You have to use the whole case statement again. I believe you can only use an alias in an Order By.
I've got a query that uses several subqueries. It's about 100 lines, so I'll leave it out. The issue is that I have several rows returned as part of one subquery that need to be joined to an integer value from the main query. Like so:
Select
... columns ...
from
... tables ...
(
select
... column ...
from
... tables ...
INNER JOIN core.Type mt
on m.TypeID = mt.TypeID
where dpt.[DataPointTypeName] = 'TheDataPointType'
and m.TypeID in (100008, 100009, 100738, 100739)
and datediff(d, m.MeasureEntered, GETDATE()) < 365 -- only care about measures from past year
and dp.DataPointValue <> ''
) as subMdp
) as subMeas
on (subMeas.DataPointValue NOT LIKE '%[^0-9]%'
and subMeas.DataPointValue = cast(vcert.IDNumber as varchar(50))) -- THIS LINE
... more tables etc ...
The issue is that if I take out the cast(vcert.IDNumber as varchar(50))) it will attempt to compare a value like 'daffodil' to a number like 3245. Even though the datapoint that contains 'daffodil' is an orphan record that should be filtered out by the INNER JOIN 4 lines above it. It works fine if I try to compare a string to a string but blows up if I try to compare a string to an int -- even though I have a clause in there to only look at things that can be converted to integers: NOT LIKE '%[^0-9]%'. If I specifically filter out the record containing 'daffodil' then it's fine. If I move the NOT LIKE line into the subquery it will still fail. It's like the NOT LIKE is evaluated last no matter what I do.
So the real question is why SQL would be evaluating a JOIN clause before evaluating a WHERE clause contained in a subquery. Also how I can force it to only evaluate the JOIN clause if the value being evaluated is convertible to an INT. Also why it would be evaluating a record that will definitely not be present after an INNER JOIN is applied.
I understand that there's a strong element of query optimizer voodoo going on here. On the other hand I'm telling it to do an INNER JOIN and the optimizer is specifically ignoring it. I'd like to know why.
The problem you are having is discussed in this item of feedback on the connect site.
Whilst logically you might expect the filter to exclude any DataPointValue values that contain any non numeric characters SQL Server appears to be ordering the CAST operation in the execution plan before this filter happens. Hence the error.
Until Denali comes along with its TRY_CONVERT function the way around this is to wrap the usage of the column in a case expression that repeats the same logic as the filter.
So the real question is why SQL would be evaluating a JOIN clause
before evaluating a WHERE clause contained in a subquery.
Because SQL engines are required to behave as if that's what they do. They're required to act like they build a working table from all of the table constructors in the FROM clause; expressions in the WHERE clause are applied to that working table.
Joe Celko wrote about this many times on Usenet. Here's an old version with more details.
First of all,
NOT LIKE '%[^0-9]%'
isn`t work well. Example:
DECLARE #Int nvarchar(20)= ' 454 54'
SELECT CASE WHEN #INT LIKE '%[^0-9]%' THEN 1 ELSE 0 END AS Is_Number
Result: 1
But it is not a number!
To check if it is real int value , you should use ISNUMERIC function. Let`s check this:
DECLARE #Int nvarchar(20)= ' 454 54'
SELECT ISNUMERIC(#int) Is_Int
Result:0
Result is correct.
So, instead of
NOT LIKE '%[^0-9]%'
try to change this to
ISNUMERIC(subMeas.DataPointValue)=0
UPDATE
How check if value is integer?
First here:
WHERE ISNUMERIC(str) AND str NOT LIKE '%.%' AND str NOT LIKE '%e%' AND str NOT LIKE '%-%'
Second:
CREATE Function dbo.IsInteger(#Value VarChar(18))
Returns Bit
As
Begin
Return IsNull(
(Select Case When CharIndex('.', #Value) > 0
Then Case When Convert(int, ParseName(#Value, 1)) <> 0
Then 0
Else 1
End
Else 1
End
Where IsNumeric(#Value + 'e0') = 1), 0)
End
Filter out the non-numeric records in a subquery or CTE