Apologies if this has been asked before - I've spent a couple of hours searching but not found anything that's helped.
It's quite simple really - I've been asked to create a query which includes a field that when it was set up (not by me) was created as a VARCHAR instead of an INT.
I need to do some calculations on this field, however some users have been entering text into it, so the calculations fail as it can't convert the data to an INT.
Is there anything I can add to a CASE statement to handle where there's text?
I was thinking something like the below, but don't know what the actual code is:
CASE
WHEN [Field1] IS TEXT THEN 1 ;
ELSE [Field2] as [Chose name]
END
Edit: Note that this is in MS SQL Server.
Thanks.
In SQL Server, you can use try_convert() and isnull() for this:
isnull(try_convert(int, field), 1)
try_convert() attempts you cast field to an int. When that fails, null is returned; you can trap that with isnull() and turn the result to 1 instead.
Note that this only works as long as field is not null (otherwise, you would get 1 as a result).
In SQL Server
Declare #Salary varchar(100);
Set #Salary = 50000;
Select Case when ISNUMERIC(#Salary) = 1 then 1
else 0 end as [Check]
May be this will be Helpful.
Related
how can I convert to T-Sql this one?
IIf([ESSValue]<>0,Int([ESSValue]*100),"")
I think the following pretty much does what you want:
select coalesce(cast(EssValue * 100 as int), 0)
Here is the thinking. The comparison to zero is unimportant, because 0 times any value is going to be zero. The iif() returns an integer (I think) because the "then" argument is an integer; the empty string gets converted to zero.
I'm not 100% certain about the last statements with regard to MS Access, but that is how iif() works in SQL Server.
I should add. Although I don't approve of iif() for conditional expressions (because case is the standard and more powerful), SQL Server does support it. So you could write:
IIf([ESSValue]<>0, cast([ESSValue]*100 as int), '')
Note: As I mentioned earlier, the '' will be converted to 0.
CASE WHEN ESSValue <> 0
THEN CAST(ESSValue * 100 AS INT)
ELSE NULL
END as fieldname
For case expression the default is NULL if doesn't meet any condition, so you dont really need the ELSE condition
I need to checking a column where numeric or not in SQL Server 2012.
This my case code.
CASE
WHEN ISNUMERIC(CUST_TELE) = 1
THEN CUST_TELE
ELSE NULL
END AS CUSTOMER_CONTACT_NO
But when the '78603D99' value is reached, it returns 1 which means SQL Server considered this string as numeric.
Why is that?
How to avoid this kind of issues?
Unfortunately, the ISNUMERIC() function in SQL Server has many quirks. It's not exactly buggy, but it rarely does what people expect it to when they first use it.
However, since you're using SQL Server 2012 you can use the TRY_PARSE() function which will do what you want.
This returns NULL:
SELECT TRY_PARSE('7860D399' AS int)
This returns 7860399
SELECT TRY_PARSE('7860399' AS int)
https://msdn.microsoft.com/en-us/library/hh213126.aspx
Obviously, this works for datatypes other than INT as well. You say you want to check that a value is numeric, but I think you mean INT.
Although try_convert() or try_parse() works for a built-in type, it might not do exactly what you want. For instance, it might allow decimal points, negative signs, and limit the length of digits.
Also, isnumeric() is going to recognize negative numbers, decimals, and exponential notation.
If you want to test a string only for digits, then you can use not like logic:
(CASE WHEN CUST_TELE NOT LIKE '%[^0-9]%'
THEN CUST_TELE
END) AS CUSTOMER_CONTACT_NO
This simply says that CUST_TELE contains no characters that are not digits.
Nothing substantive to add but a couple warnings.
1) ISNUMERIC() won't catch blanks but they will break numeric conversions.
2) If there is a single non-numeric character in the field and you use REPLACE to get rid of it you still need to handle the blank (usually with a CASE statement).
For instance if the field contains a single '-' character and you use this:
cast(REPLACE(myField, '-', '') as decimal(20,4)) myNumField
it will fail and you'll need to use something like this:
CASE WHEN myField IN ('','-') THEN NULL ELSE cast(REPLACE(myField, '-', '') as decimal(20,4)) END myNumField
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
I've got a report that has been in use quite a while - in fact, the company's invoice system rests in a large part upon this report (Disclaimer: I didn't write it). The filtering is based upon whether a field of type VarChar(50) falls between two numeric values passed in by the user.
The problem is that the field the data is being filtered on now not only has simple non-numeric values such as '/A', 'TEST' and a slew of other non-numeric data, but also has numeric values that seem to be defying any type of numeric conversion I can think of.
The following (simplified) test query demonstrates the failure:
Declare #StartSummary Int,
#EndSummary Int
Select #StartSummary = 166285,
#EndSummary = 166289
Select SummaryInvoice
From Invoice
Where IsNull(SummaryInvoice, '') <> ''
And IsNumeric(SummaryInvoice) = 1
And Convert(int, SummaryInvoice) Between #StartSummary And #EndSummary
I've also attempted conversions using bigint, real and float and all give me similar errors:
Msg 8115, Level 16, State 2, Line 7
Arithmetic overflow error converting
expression to data type int.
I've tried other larger numeric datatypes such as BigInt with the same error. I've also tried using sub-queries to sidestep the conversion issue by only extracting fields that have numeric data and then converting those in the wrapper query, but then I get other errors which are all variations on a theme indicating that the value stored in the SummaryInvoice field can't be converted to the relevant data type.
Short of extracting only those records with numeric SummaryInvoice fields to a temporary table and then querying against the temporary table, is there any one-step solution that would solve this problem?
Edit: Here's the field data that I suspect is causing the problem:
SummaryInvoice
11111111111111111111111111
IsNumeric states that this field is numeric - which it is. But attempting to convert it to BigInt causes an arithmetic overflow. Any ideas? It doesn't appear to be an isolated incident, there seems to have been a number of records populated with data that causes this issue.
It seems that you are gonna have problems with the ISNUMERIC function, since it returns 1 if can be cast to any number type (including ., ,, e0, etc). If you have numbers longer than 2^63-1, you can use DECIMAL or NUMERIC. I'm not sure if you can use PATINDEX to perform an regex look on SummaryInvoice, but if you can, then you should try this:
SELECT SummaryInvoice
FROM Invoice
WHERE ISNULL(SummaryInvoice, '') <> ''
AND CASE WHEN PATINDEX('%[^0-9]%',SummaryInvoice) > 0 THEN CONVERT(DECIMAL(30,0), SummaryInvoice) ELSE -1 END
BETWEEN #StartSummary And #EndSummary
You can't guarantee what order the WHERE clause filters will be applied.
One ugly option to decouple inner and outer.
SELECT
*
FROM
(
Select TOP 2000000000
SummaryInvoice
From Invoice
Where IsNull(SummaryInvoice, '') <> ''
And IsNumeric(SummaryInvoice) = 1
ORDER BY SummaryInvoice
) foo
WHERE
Convert(int, SummaryInvoice) Between #StartSummary And #EndSummary
Another using CASE
Select SummaryInvoice
From Invoice
Where IsNull(SummaryInvoice, '') <> ''
And
CASE WHEN IsNumeric(SummaryInvoice) = 1 THEN Convert(int, SummaryInvoice) ELSE -1 END
Between #StartSummary And #EndSummary
YMMV
Edit: after question update
use decimal(38,0) not int
Change ISNUMERIC(SummaryInvoice) to ISNUMERIC(SummaryInvoice + '0e0')
AND with IsNumeric(SummaryInvoice) = 1, will not short circuit in SQL Server.
But may be you can use
AND (CASE IsNumeric(SummaryInvoice) = 1 THEN Convert(int, SummaryInvoice) ELSE 0 END)
Between #StartSummary And #EndSummary
Your first issue is to fix your database structure so bad data cannot get into the field. You are putting a band-aid on a wound that needs stitches and wondering why it doesn't heal.
Database refactoring is not fun, but it needs to be done when there is a data integrity problem. I assume you aren't really invoicing someone for 11,111,111,111,111,111,111,111,111 or 'test'. So don't allow those values to ever get entered (if you can't change the structure to the correct data type, consider a trigger to prevent bad data from going in) and delete the ones you do have that are bad.
I'm selecting a value out of a table that can either be an integer or a nvarchar. It's stored as nvarchar. I want to conditionally call a function that will convert this value if it is an integer (that is, if it can be converted into an integer), otherwise I want to select the nvarchar with no conversion.
This is hitting a SQL Server 2005 database.
select case
when T.Value (is integer) then SomeConversionFunction(T.Value)
else T.Value
end as SomeAlias
from SomeTable T
Note that it is the "(is integer)" part that I'm having trouble with. Thanks in advance.
UPDATE
Check the comment on Ian's answer. It explains the why and the what a little better. Thanks to everyone for their thoughts.
select case
when ISNUMERIC(T.Value) then T.Value
else SomeConversionFunction(T.Value)
end as SomeAlias
Also, have you considered using the sql_variant data type?
The result set can only have one type associated with it for each column, you will get an error if the first row converts to an integer and there are strings that follow:
Msg 245, Level 16, State 1, Line 1
Conversion failed when converting the nvarchar value 'word' to data type int.
try this to see:
create table testing
(
strangevalue nvarchar(10)
)
insert into testing values (1)
insert into testing values ('word')
select * from testing
select
case
when ISNUMERIC(strangevalue)=1 THEN CONVERT(int,strangevalue)
ELSE strangevalue
END
FROM testing
best bet is to return two columns:
select
case
when ISNUMERIC(strangevalue)=1 THEN CONVERT(int,strangevalue)
ELSE NULL
END AS StrangvalueINT
,case
when ISNUMERIC(strangevalue)=1 THEN NULL
ELSE strangevalue
END AS StrangvalueString
FROM testing
or your application can test for numeric and do your special processing.
You can't have a column that is sometimes an integer and sometimes a string. Return the string and check it using int.TryParse() in the client code.
ISNUMERIC. However, this accepts +, - and decimals so more work is needed.
However, you can't have the columns as both datatypes in one go: you'll need 2 columns.
I'd suggest that you deal with this in your client or use an ISNUMERIC replacement
IsNumeric will get you part of the way there. You can then add some further code to check whether it is an integer
for example:
select top 10
case
when isnumeric(mycolumn) = 1 then
case
when convert(int, mycolumn) = mycolumn then
'integer'
else
'number but not an integer'
end
else
'not a number'
end
from mytable
To clarify some other answers, your SQL statement can't return different data types in one column (it looks like the other answers are saying you can't store different data types in one column - yours are all strign represenations).
Therefore, if you use ISNUMERIC or another function, the value will be cast as a string in the table that is returned anyway if there are other strigns being selected.
If you are selecting only one value then it could return a string or a number, however your front end code will need to be able to return the different data types.
Just to add to some of the other comments about not being able to return different data types in the same column... Database columns should know what datatype they are holding. If they don't then that should be a BIG red flag that you have a design problem somewhere, which almost guarantees future headaches (like this one).