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RE: Conversion Fun

Bhavesh_Patel — Sat, 21 Nov 2009 02:14:39 GMT

Yeap, I got it!

RE: Conversion Fun

SanDroid — Wed, 12 Aug 2009 12:09:39 GMT

"Conversion failed when converting the varchar value '0,.0' to data type int."No SQL product that I could find returned "error converting to a numeric" when trying to convert a varchar value to Int.Why make the correct answer wrong?Are you practicing up to write certification exam questions where the least wrong answer is the right one?

RE: Conversion Fun

Darpan Sarin — Tue, 11 Aug 2009 01:13:53 GMT

ISNUMERIC() checks whether the input is valid numeric data, that also includes money data type, thats why it used to return 1 for isnumeric('0,.0') cause its a valid money type. On the other hand integer data type is limited to numbers only...

RE: Conversion Fun

Christian Buettner-167247 — Tue, 11 Aug 2009 00:09:56 GMT

That is actually a good question and unfortunately I have no idea :(

RE: Conversion Fun

kevin.l.williams — Mon, 10 Aug 2009 10:18:11 GMT

[quote][b]Christian Buettner (8/10/2009)[/b][hr]Hi Kevin,I think that is not true.Try [code]select isnumeric('$$')[/code] for example.It will evaluate to false, although this character ($) was no issue in your previous example.The reason why your example is returning true, is probably the fact that it can be cast to (small)money.[/quote]My mistake. Thanks for pointing this out. I always thought this function just didn't work properly. Now I see I just didn't understand it's purpose. Any idea why Microsoft didn't implement ISMONEY() ISINT() or ISFLOAT()? ISNUMERIC() seems almost useless for testing before an insert.

RE: Conversion Fun

kramaswamy — Mon, 10 Aug 2009 05:24:32 GMT

[quote]Try finding an example that is not convertible to a numeric datatype but that returns true in this function.[/quote]That's impossible :P as per the definition of the function, ISNUMERIC only returns true if the input is convertible to one of the numeric data types.

RE: Conversion Fun

Christian Buettner-167247 — Mon, 10 Aug 2009 00:59:29 GMT

[quote][b]kevin.l.williams (8/7/2009)[/b][hr]isnumeric is just evaluating valid characters. This will produce 1 also[code]select isnumeric('-$,')[/code][/quote]Hi Kevin,I think that is not true.Try [code]select isnumeric('$$')[/code] for example.It will evaluate to false, although this character ($) was no issue in your previous example.The reason why your example is returning true, is probably the fact that it can be cast to (small)money.Try finding an example that is not convertible to a numeric datatype but that returns true in this function.

RE: Conversion Fun

hakan.winther — Sat, 08 Aug 2009 09:12:53 GMT

I encountered this issue a couple of month ago and i solved it with the following udf from ASPFAQ.com [url=http://classicasp.aspfaq.com/general/what-is-wrong-with-isnumeric.html][/url][code]CREATE FUNCTION dbo.isReallyNumeric ( @num VARCHAR(64) ) RETURNS BIT BEGIN IF LEFT(@num, 1) = '-' SET @num = SUBSTRING(@num, 2, LEN(@num)) DECLARE @pos TINYINT SET @pos = 1 + LEN(@num) - CHARINDEX('.', REVERSE(@num)) RETURN CASE WHEN PATINDEX('%[^0-9.-]%', @num) = 0 AND @num NOT IN ('.', '-', '+', '^') AND LEN(@num)>0 AND @num NOT LIKE '%-%' AND ( ((@pos = LEN(@num)+1) OR @pos = CHARINDEX('.', @num)) ) THEN 1 ELSE 0 END END GO CREATE FUNCTION dbo.isReallyInteger ( @num VARCHAR(64) ) RETURNS BIT BEGIN IF LEFT(@num, 1) = '-' SET @num = SUBSTRING(@num, 2, LEN(@num)) RETURN CASE WHEN PATINDEX('%[^0-9-]%', @num) = 0 AND CHARINDEX('-', @num) <= 1 AND @num NOT IN ('.', '-', '+', '^') AND LEN(@num)>0 AND @num NOT LIKE '%-%' THEN 1 ELSE 0 END END [/code]

RE: Conversion Fun

john.moreno — Fri, 07 Aug 2009 11:47:51 GMT

I'd like to seee the explanation expanded to explain that [code]select convert(money,'0,.0')[/code] would work, and that is why isNumeric is returning true (i.e. that isnumeric is ignoring the comma because that's what convert does for money).Try: [code]select convert(money,'0,,,0,.0,,,0')[/code]

RE: Conversion Fun

Michael Poppers — Fri, 07 Aug 2009 10:17:00 GMT

[quote][b]ronmoses (8/7/2009)[/b][hr]Dang it, I knew that was the answer and didn't pick it. That seemed like the obvious "otherwise, why would I ask the question?" answer. But no, I had to go and [i]think[/i] about it. Stupid me. :-)[/quote]Ditto :-). That said, I would love to hear from the people who thought the answer for a CONVERT(int, {anything}) would be either 0.0 or 0,.0!

RE: Conversion Fun

kevin.l.williams — Fri, 07 Aug 2009 10:07:03 GMT

isnumeric is just evaluating valid characters. This will produce 1 also[code]select isnumeric('-$,')[/code]

RE: Conversion Fun

kramaswamy — Fri, 07 Aug 2009 09:19:00 GMT

It's just the way that SQL Server deals with Monetary data. It's always got four trailing spaces for decimals, and the decimal symbol (".") is interpreted as being the symbol to indicate that you're dealing with the decimal part of the Money value, while the comma (",") is treated as being part of the non-decimal part.EG: 1,000 is the same as 1000, while 1.000 is the same as 1, and 1,000.1 is the same as 1000.1

RE: Conversion Fun

SanjayAttray — Fri, 07 Aug 2009 08:38:44 GMT

[quote][b]Christian Buettner (8/7/2009)[/b][hr]If I am not totally wrong, the behaviour is not due to IsNumeric itself, but to the fact that you can cast this value to money or smallmoney.Try this:[code]SET NOCOUNT ONSELECT CONVERT(money ,'1,0.2') A, CONVERT(money ,'1.0,2') B, CONVERT(money ,'1,100,00.2') C[/code][quote][font="Courier New"]A.......B......C..........10.2000 1.0200 110000.2000[/font][/quote]Now dont ask me why...[/quote]Very interesting. Never thought or tried it or say never came across this kind of issue. Not to you Chris, but to some one else who could give better explanation.My question - Why ?

RE: Conversion Fun

Rob Goddard — Fri, 07 Aug 2009 07:10:53 GMT

I agree with the above post, integer is very specific, in fact forget the odd character, even [code]select convert(int,'0.0')[/code] will not work. [code]select convert(decimal(2,1),'0,.0')[/code] will give the error that was supplied as one of the answers to the question.Interestingly (or not, it is Friday lunch time), money to int will work no worries, rounding to the nearest int, so [code]select convert(int,convert(money,'0,.0'))[/code] will work fine if you're worried about isnumeric letting you down! :hehe:

RE: Conversion Fun

kramaswamy — Fri, 07 Aug 2009 06:30:43 GMT

Essentially, the reason why it doesn't work is because an integer is a subset of the numeric datatypes, and not vice-versa. Things which are numeric are not necessarily integers, while all integers are numeric.

RE: Conversion Fun

Aaron N. Cutshall — Fri, 07 Aug 2009 06:28:58 GMT

I don't believe that isnumeric looks at the string as a whole, but as the individual characters in the string. I think it's a rather broad assertion that the string [b][i][u]COULD[/u][/i][/b] be converted to a number of some fashion (integer, real, money, etc.).

RE: Conversion Fun

ronmoses — Fri, 07 Aug 2009 05:50:42 GMT

Dang it, I knew that was the answer and didn't pick it. That seemed like the obvious "otherwise, why would I ask the question?" answer. But no, I had to go and [i]think[/i] about it. Stupid me. :-)

RE: Conversion Fun

Christian Buettner-167247 — Fri, 07 Aug 2009 05:47:56 GMT

If I am not totally wrong, the behaviour is not due to IsNumeric itself, but to the fact that you can cast this value to money or smallmoney.Try this:[code]SET NOCOUNT ONSELECT CONVERT(money ,'1,0.2') A, CONVERT(money ,'1.0,2') B, CONVERT(money ,'1,100,00.2') C[/code][quote][font="Courier New"]A.......B......C..........10.2000 1.0200 110000.2000[/font][/quote]Now dont ask me why...

RE: Conversion Fun

kramaswamy — Fri, 07 Aug 2009 05:37:42 GMT

[quote][b]srikanth_pallerla (8/7/2009)[/b][hr]why isnumeric gives true when the content contains ','. May be question seems simple but i am new to sql server.[/quote]As per the Books Online page (http://msdn.microsoft.com/en-us/library/ms186272.aspx):"ISNUMERIC returns 1 when the input expression evaluates to a valid numeric data type; otherwise it returns 0."Valid numeric data types include things like Money data types - "ISNUMERIC returns 1 for some characters that are not numbers, such as plus (+), minus (-), and valid currency symbols such as the dollar sign ($). For a complete list of currency symbols, see Using Monetary Data."Integer is a pretty specific data type. It won't accept things that are considered Numeric in some cases. If you need the ability to detect whether something is an Integer, I'd suggest writing your own UDF. There's many different ways to do it. One thing you can do is to cast the value to a VARCHAR data type, then loop through every character, and see if every character evaluates to an ASCII value between 48 and 57 (numbers 0-9); if any don't,then you'll know that it's not an Integer.

RE: Conversion Fun

Todd Heidesch — Fri, 07 Aug 2009 04:42:58 GMT

I suspect this is due to the way it handles foreign numbers. When I work with countries using format '0,0' I want it to treat it as numeric based on the server regional settings. Unfortunately, it is more likely that isnumeric() is taking naughty shortcuts and replacing certain characters like the comma - regardless of server settings - whereas convert() is not.

RE: Conversion Fun

srikanth_pallerla-1082904 — Fri, 07 Aug 2009 04:37:19 GMT

why isnumeric gives true when the content contains ','. May be question seems simple but i am new to sql server.

RE: Conversion Fun

ChiragNS — Fri, 07 Aug 2009 04:28:13 GMT

just 3 days back i had a similar issue with isnumeric. If this QOTD had come then it would have been helpful.

RE: Conversion Fun

Joy Smith San — Fri, 07 Aug 2009 02:54:07 GMT

..And answer is in the subject itself...................

RE: Conversion Fun

SQLPhil — Fri, 07 Aug 2009 02:00:30 GMT

But aren't you trying to convert it to an integer in the code you supplied rather than a numeric data type?Granted you'll still get the error but if you run the code you'll get the response "Conversion failed when converting the varchar value '0,.0' to data type int" which isn't one of the available answers.

Conversion Fun

SuperDBA-207096 — Fri, 07 Aug 2009 00:21:44 GMT

Comments posted to this topic are about the item [B]Conversion Fun[/B]