Check if a varchar is a number (T-SQL) - tsql

Question

Is there an easy way to figure out if a varchar is a number?
Examples:
abc123 --> no number
123 --> yes, its a number

Answer 1

ISNUMERIC will not do - it tells you that the string can be converted to any of the numeric types, which is almost always a pointless piece of information to know. For example, all of the following are numeric, according to ISNUMERIC:
£, $, 0d0
If you want to check for digits and only digits, a negative LIKE expression is what you want:
not Value like '%[^0-9]%'

Answer 2

ISNUMERIC will do
Check the NOTES section too in the article.

Answer 3

You can check like this:
declare #vchar varchar(50)
set #vchar ='34343';
select case when #vchar not like '%[^0-9]%' then 'Number' else 'Not a Number' end

Answer 4

Using SQL Server 2012+, you can use the TRY_* functions if you have specific needs. For example,
-- will fail for decimal values, but allow negative values
TRY_CAST(#value AS INT) IS NOT NULL
-- will fail for non-positive integers; can be used with other examples below as well, or reversed if only negative desired
TRY_CAST(#value AS INT) > 0
-- will fail if a $ is used, but allow decimals to the specified precision
TRY_CAST(#value AS DECIMAL(10,2)) IS NOT NULL
-- will allow valid currency
TRY_CAST(#value AS MONEY) IS NOT NULL
-- will allow scientific notation to be used like 1.7E+3
TRY_CAST(#value AS FLOAT) IS NOT NULL

Answer 5

I ran into the need to allow decimal values, so I used not Value like '%[^0-9.]%'

Answer 6

Wade73's answer for decimals doesn't quite work. I've modified it to allow only a single decimal point.
declare #MyTable table(MyVar nvarchar(10));
insert into #MyTable (MyVar)
values
(N'1234')
, (N'000005')
, (N'1,000')
, (N'293.8457')
, (N'x')
, (N'+')
, (N'293.8457.')
, (N'......');
-- This shows that Wade73's answer allows some non-numeric values to slip through.
select * from (
select
MyVar
, case when MyVar not like N'%[^0-9.]%' then 1 else 0 end as IsNumber
from
#MyTable
) t order by IsNumber;
-- Notice the addition of "and MyVar not like N'%.%.%'".
select * from (
select
MyVar
, case when MyVar not like N'%[^0-9.]%' and MyVar not like N'%.%.%' then 1 else 0 end as IsNumber
from
#MyTable
) t
order by IsNumber;

Answer 7

Damien_The_Unbeliever noted that his was only good for digits
Wade73 added a bit to handle decimal points
neizan made an additional tweak as did notwhereuareat.
Unfortunately, none appear to handle negative values and they appear to have issues with a comma in the value...
Here's my tweak to pick up negative values and those with commas
declare #MyTable table(MyVar nvarchar(10));
insert into #MyTable (MyVar)
values
(N'1234')
, (N'000005')
, (N'1,000')
, (N'293.8457')
, (N'x')
, (N'+')
, (N'293.8457.')
, (N'......')
, (N'.')
, (N'-375.4')
, (N'-00003')
, (N'-2,000')
, (N'3-3')
, (N'3000-')
;
-- This shows that Neizan's answer allows "." to slip through.
select * from (
select
MyVar
, case when MyVar not like N'%[^0-9.]%' then 1 else 0 end as IsNumber
from
#MyTable
) t order by IsNumber;
-- Notice the addition of "and MyVar not like '.'".
select * from (
select
MyVar
, case when MyVar not like N'%[^0-9.]%' and MyVar not like N'%.%.%' and MyVar not like '.' then 1 else 0 end as IsNumber
from
#MyTable
) t
order by IsNumber;
--Trying to tweak for negative values and the comma
--Modified when comparison
select * from (
select
MyVar
, case
when MyVar not like N'%[^0-9.,-]%' and MyVar not like '.' and isnumeric(MyVar) = 1 then 1
else 0
end as IsNumber
from
#MyTable
) t
order by IsNumber;

Answer 8

DECLARE #A nvarchar(100) = '12'
IF(ISNUMERIC(#A) = 1)
BEGIN
PRINT 'YES NUMERIC'
END

Answer 9

Neizan's code lets values of just a "." through. At the risk of getting too pedantic, I added one more AND clause.
declare #MyTable table(MyVar nvarchar(10));
insert into #MyTable (MyVar)
values
(N'1234')
, (N'000005')
, (N'1,000')
, (N'293.8457')
, (N'x')
, (N'+')
, (N'293.8457.')
, (N'......')
, (N'.')
;
-- This shows that Neizan's answer allows "." to slip through.
select * from (
select
MyVar
, case when MyVar not like N'%[^0-9.]%' then 1 else 0 end as IsNumber
from
#MyTable
) t order by IsNumber;
-- Notice the addition of "and MyVar not like '.'".
select * from (
select
MyVar
, case when MyVar not like N'%[^0-9.]%' and MyVar not like N'%.%.%' and MyVar not like '.' then 1 else 0 end as IsNumber
from
#MyTable
) t
order by IsNumber;

Answer 10

Do not forget to exclude carriage returns from your data!
As in:
SELECT
Myotherval
, CASE WHEN TRIM(REPLACE([MyVal], char(13) + char(10), '')) not like '%[^0-9]%' and RTRIM(REPLACE([MyVal], char(13) + char(10), '')) not like '.' and isnumeric(REPLACE([MyVal], char(13) + char(10), '')) = 1 THEN 'my number: ' + [MyVal]
ELSE ISNULL(Cast([MyVal] AS VARCHAR(8000)), '')
END AS 'MyVal'
FROM MyTable

Answer 11

In case you want to add a constraint on a field:
Positive integer with fixed length
ALTER TABLE dbo.BankBranchType
ADD CONSTRAINT CK_TransitNumberMustBe5Digits
CHECK (TransitNumber NOT like '%[^0-9]%'
AND LEN(TransitNumber) = 5)

Answer 12

To check the Number, Currency, and Amount, use the below SQL fragment.
#value NOT LIKE '%[^0-9.,]%'
For a quick win, refer to the below example:
Function example:
CREATE FUNCTION [dbo].[fnCheckValueIsNumber](
#value NVARCHAR(255)=NULL
)RETURNS INT AS BEGIN
DECLARE #ReturnValue INT=0
IF EXISTS (SELECT * WHERE #value NOT LIKE '%[^0-9.,]%') SELECT #ReturnValue=1
RETURN #ReturnValue;
Execution result
SELECT [dbo].[fnCheckValueIsNumber]('12345')
RESULT = 1
SELECT [dbo].[fnCheckValueIsNumber]('10020.25')
RESULT = 1
SELECT [dbo].[fnCheckValueIsNumber]('10,020.25')
RESULT = 1
SELECT [dbo].[fnCheckValueIsNumber]('12,345ABCD')
RESULT = 0