T-sql - determine if value is integer

Question

I want to determine if a value is integer (like TryParse in .NET). Unfortunatelly ISNUMERIC does not fit me because I want to parse only integers a

Answer 1

WHERE IsNumeric(MY_FIELD) = 1 AND CAST(MY_FIELD as VARCHAR(5)) NOT LIKE '%.%'

That is probably the simplest solution. Unless your MY_FIELD contains .00 or something of that sort. In which case, cast it to a float to remove any trailing .00s

Answer 2

As of SQL Server 2012, the TRY_CONVERT and TRY_CAST functions were implemented. Thise are vast improvements over the ISNUMERIC solution, which can (and does) give false positives (or negatives). For example if you run the below:

SELECT CONVERT(int,V.S)
FROM (VALUES('1'),
            ('900'),
            ('hello'),
            ('12b'),
            ('1.1'),
            ('')) V(S)
WHERE ISNUMERIC(V.S) = 1;

Using TRY_CONVERT (or TRY_CAST) avoids that:

SELECT TRY_CONVERT(int,V.S),
       V.S,
       ISNUMERIC(V.S)
FROM (VALUES('1'),
            ('900'),
            ('hello'),
            ('12b'),
            ('1.1'),
            ('')) V(S)
--WHERE TRY_CONVERT(int,V.S) IS NOT NULL; --To filter to only convertable values

Notice that '1.1' returned NULL, which cause the error before (as a string represtation of a decimal cannot be converted to an int) but also that '' returned 0, even though ISNUMERIC states the value "can't be converted".

Answer 3

I think that there is something wrong with your database design. I think it is a really bad idea to mix varchar and numbers in one column? What is the reason for that?

Of course you can check if there are any chars other than [0-9], but imagine you have a 1m rows in table and your are checking every row. I think it won't work well.

Anyway if you really want to do it I suggest doing it on the client side.

Answer 4

I am not a Pro in SQL but what about checking if it is devideable by 1 ? For me it does the job.

SELECT *
FROM table    
WHERE fieldname % 1 = 0

Answer 5

This works fine in SQL Server

SELECT (SELECT ISNUMERIC(2) WHERE ISNUMERIC(2)=1 AND 2 NOT LIKE '%.%')

Answer 6

See whether the below query will help

SELECT *
FROM MY_TABLE
WHERE CHARINDEX('.',MY_FIELD) = 0 AND CHARINDEX(',',MY_FIELD) = 0       
AND ISNUMERIC(MY_FIELD) = 1 AND CONVERT(FLOAT,MY_FIELD) / 2147483647 <= 1