following situation:
a column xy is defined as varchar(25). In a view (SQL Server Mgmt Studio 2008) I filtered all values with letters (-> is not like '%[A-Z]%') and converted it to int (cast(xy as int)).
If I now try to make comprisons with that column (e.g. where xy < 1000), I'm getting a conversion error. And the message contains a value that should have been filtered with "is not like '%[A-Z]%'". Whats wrong??
thanks for help in advance...
this works (it folters out for example value 'G8111'):
SELECT unid
FROM CD_UNITS AS a INNER JOIN DEF_STATION AS b ON a.STATION = b.STATION
WHERE (b.CURENT = 'T') and UNID like '%[A-Z]%'
but when i put that in a view, an make select on it:
select * from my_view where xy < 3000
system says 'Conversion failed when converting the varchar value 'G8111' to data type int.' but 'G8111' should be filtered out in query above...
The optimizer does crazy things at times, so despite the fact that an "inner" filter1 "should" protect you, the optimizer may still push the conversion lower down than the filter and cause such errors.
The only semi-documented place where it will not do this is within a CASE expression:
The CASE statement(sic) evaluates its conditions sequentially and stops with the first condition whose condition is satisfied. In some situations, an expression is evaluated before a CASE statement receives the results of the expression as its input.
...
You should only depend on order of evaluation of the WHEN conditions for scalar expressions (including non-correlated sub-queries that return scalars), not for aggregate expressions
So the only way that should currently work would be:
CASE WHEN xy NOT LIKE '%[^0-9]%' THEN CONVERT(int,xy) END < 1000
This also uses a double-negative with LIKE to ensure that it only attempts the conversion when the value only contains digits.
1Whether this be in a subquery, a CTE, a View, or even just considering the logical processing order of SELECT and WHERE clauses. Within a single query, the optimizer can and will push conversion operations past filters.
Related
I have a database with MANY out-of-date file locations. The difference between the out-of-date file locations and the correct locations is simply the left-side of the address. So, I am attempting to take the left-side off and replace it with the correct string. But, I can't get there because my query is altering the right-side of the address.
This query is made using "vfpoledb."
SELECT RIGHT(LINK,LEN(LINK)-8) ,LEN(LINK)-8,RIGHT(LINK,77),LINK
FROM LINKSTORE
WHERE DOCLBL = "V46145002A"
This query returns the following:
EXP1:
\SHARES\DATA\QMS\QMS DATA\TRACKING FILES\REMOTEENTRIES\V46145 216447
EXP2:
77
EXP3:
\SHARES\DATA\QMS\QMS DATA\TRACKING FILES\REMOTEENTRIES\V46145 216447-002A.PDF
LINK:
\\SERVER\SHARES\DATA\QMS\QMS DATA\TRACKING FILES\REMOTEENTRIES\V46145 216447-002A.PDF
I don't understand why EXP1 and EXP3 are giving different results. EXP3 is what I'm looking for EXP1 to return. If I could get that, I could append the correct left-hand-side and create an update query to fix everything.
Edit:
Even when changing the query to:
SELECT RIGHT(LINK,LEN(LINK)) ,LEN(LINK)-8,RIGHT(LINK,77),LINK
FROM LINKSTORE
WHERE DOCLBL = "V46145002A"
The link still cuts off at the same point, which is odd because expression_3 which still uses Right(), but manually provides the length instead of using Len() does not do this.
Furthermore, it seems that when I run the query to include all results:
SELECT RIGHT(LINK,LEN(LINK)) ,LEN(LINK)-8,RIGHT(LINK,77),LINK
FROM LINKSTORE
WHERE 1=1
All values returned by Exp1 are equal in length even though Exp2 and Link are different in size.
So back to the problem, how can I run a query to replace the left-side with the correct server if I can't separate them out?
OK this is tricky, I did some Foxpro 20 years ago but don't have it to hand.
Your SELECT statement looks OK to me. In the comments under the question Thomas G created this DbFiddle which shows that in a 'normal' dbms, your SELECT statement gives the result you are expecting: https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=37047d2b7efb91aaa029fa0fb98eea24
So the problem must be something FoxPro/dBase specific rather than a problem with your SELECT statement.
Reading up I see people say that with FoxPro always use ALLTRIM() when using RIGHT() or LEN() on table fields because the data gets returned padded with spaces. I don't see how that would cause the exact bug you're seeing but you could try this maybe:
SELECT RIGHT(ALLTRIM(LINK),LEN(ALLTRIM(LINK))-8) ,LEN(ALLTRIM(LINK))-8,RIGHT(ALLTRIM(LINK),77),ALLTRIM(LINK)
FROM LINKSTORE
WHERE DOCLBL = "V46145002A"
edit: OK I got a better idea - are there other rows in your result set?
According to this: https://www.tek-tips.com/viewthread.cfm?qid=1706948 ... when you do SELECT (expr) in FoxPro whatever the length of the expr in the first row becomes that max length for that 'field' and so all subsequent rows get truncated to that length. Makes sense in a crazy 1970s sort of way.
So perhaps you have a row of data above the one we are talking about which comes out at 68 chars long and so every subsequent value gets truncated to that length.
The way around it is to pad your expression results with CAST or PADR:
SELECT PADR(RIGHT(ALLTRIM(LINK),LEN(ALLTRIM(LINK))-8),100),LEN(ALLTRIM(LINK))-8,PADR(RIGHT(ALLTRIM(LINK),77),100),LINK
FROM LINKSTORE
WHERE DOCLBL = "V46145002A"
Or same without the ALLTRIM()
SELECT PADR(RIGHT(LINK,LEN(LINK)-8),100),LEN(LINK)-8,PADR(RIGHT(LINK,77),100),LINK
FROM LINKSTORE
WHERE DOCLBL = "V46145002A"
I've been tasked with creating a report for my company. The report is generated from the results returned by the Stored Procedure spGenerateReport, which has multiple filters.
Inside the SP, this is how the filter is expected to work:
SELECT * FROM MyTable WHERE column1 IN (
'filters', 'for', 'this', 'report'
)
Entering the code above yields ~30000 rows in 9s. However, I want to be able to change my SP's filter by passing it a single argument (since I may use 1 or 2 or n filters), like so:
spGenerateReport 'Filters,for,this,report'
For this I have the User-Created Function fnSplitString (yes, I do know that there is a STRING_SPLIT function but I can't use it due to a lower compatibility level of my database) which splits a single string into a table, like so:
SELECT splitData FROM fnSplitString('Filters,for,this,report')
Returns:
splitData
------
Filters
for
this
report
Thus the final code in my SP is:
SELECT * FROM MyTable WHERE column1 IN (
SELECT * FROM fnSplitString('Filters,for,this,report')
)
However, this instead yields ~10000 rows in 60s. The time taken to complete this SP is weird but isn't too much of a problem, however nearly a quarter of my rows disappearing into the void certainly is. The results only have rows from the first couple filters (for example, 'Filters' and 'for'; if I change the order of the arguments (e.g.: fnSplitString('report,for,Filters,this')), I get a different number of rows, and only from filters 'report', 'for', 'Filters'! I don't understand why using the function returns different results than those obtained when using the literal strings. Is there some inside gimmick that I'm not aware of?
PS - I'm sorry in advance for being bad at explaining myself, and for any grammar mistakes
You should definitely be getting the same results with both techniques. Something is wrong.
You havent posted the fnSplitString code but I suspect fnSplitString is not outputting the last string in the list, or maybe the last string in the list is being truncated before it reaches fnSplitString so that no matches are found.
e.g. if the parameter going into your spGenerateReport stored procedure is varchar(20) then what will reach the function is 'Filters,for,this,rep' with the last bit truncated.
SSRS, for example, will truncate strings that are being passed into an SP instead of warning you with an error message
I have a data source like following
If I ran the following sql query it removes all the records with "Seg Type" MOD and ignores the Fnn range given.
select * from NpsoQueue
where SegmentType not in ('MOD')
and Fnn not between 0888452158 and 0888452158
I want the query to consider both conditions. So, if I ran the query it should remove only the first record
The logic in your where clause is incorrect
Use
select * from NpsoQueue
where NOT (
SegmentType = 'MOD'
and Fnn between '0888452158' and '0888452158'
)
Also, a number with a leading zero is a string literal so you need to put single quotes around it to preserve the leading zero and stop implicit casts happening
As mentioned by #TriV you could also use OR. These are fundamental boolean logic concepts, i.e. not related to SQL Server or databases
I am using a tool to produce SQL queries and I need to filter one of the queries with a multiple parameters.
The query is similar to this:
Select *
From Products
Where (#ProductTypeIds is null or Product.ProductTypeId in (#ProductTypeIds))
I know the above query is not correct on a traditional SQL, read on..
Essentially, I'm trying to apply a filter where if nothing is passed for #ProductTypeIds parameter, the where condition is not applied.
When multiple parameters are being passed, though, #ProductTypeIds is being translated by the tool into the following query:
Select *
From Products
Where (#ProductTypeIds1, #ProductTypeIds2 is null or Product.ProductTypeId in (#ProductTypeIds1, #ProductTypeIds2))
Which is clearly an invalid query. So I thought I could be clever and use COALESCE to check if they are null:
Select *
From Products
Where (COALESCE(#ProductTypeIds, null) is null or Product.ProductTypeId in (#ProductTypeIds))
This query is being translated correctly, however, now my use of COALESCE throws an error:
At least one of the arguments to COALESCE must be an expression that is not the NULL constant.
How can I efficiently check that #ProductTypeIds (which be being translated into #ProductTypeIds1, #ProductTypeIds2 is all null so I can apply the filter or ignore?
In other words, is there a way to Distinct a list of parameters to check if the final result is null ?
Thanks
I have no idea how your tool works, but try the following.
Instead of checking for null check for the value that will never come in your params like:
WHERE COALESCE(#ProductTypeIds1, #ProductTypeIds2, -666) == -666 OR ...
I am trying to connect a Filemaker DB to Firebird SQL DB in both ways import to FM and export back to Firebird DB.
So far it works using the MBS Plug-in but FM 13 Pro canot handle NULL.
That means that for example Timestamp fields that are empty (NULL) produce a "0" value.
Thats means in Time something like 01.01.1889 00:00:00.
So my idea was to simply ignore fields containing NULL.
But here my poor knowlege stops.
First I thought I can do this with WHERE, but this is ignoring whole records sets:
SELECT * FROM TABLE WHERE FIELD IS NOT NULL
Also I tried to filter it later on like this:
If (IsEmpty (MBS("SQL.GetFieldAsDateTime"; $command; "FIELD") ) = 0 ; MBS("SQL.GetFieldAsDateTime"; $command; "FIELD"))
With no result either.
This is a direct answer to halfbit's suggestion, which is correct but not for this SQL dialect. In a query to provide a replacement value when a field is NULL you need to use COALESCE(x,y). Where if X is null, Y will be used, and if Y is null then the field is NULL. Thats why it is common for me to use it like COALESCE(table.field,'') such that a constant is always outputted if table.field happens to be NULL.
select COALESCE(null,'Hello') as stackoverflow from rdb$database
You can use COALESCE() for more than two arguments, I just used two for conciseness.
I dont know the special SQL dialect, but
SELECT field1, field2, value(field, 0), ...FROM TABLE
should help you:
value gives the first argument, ie, your field if it is NOT NULL or the second argument if it is.