Check if a varchar is a number

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

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_CONVERT(INT, @value,) > 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_CONVERT(MONEY,@value) IS NOT NULL  

-- will allow scientific notation to be used like 1.7E+3
TRY_CAST(@value AS FLOAT) IS NOT NULL 

Answer 2

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

Answer 3

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 4

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 5

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 6

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 7

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 8

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 9

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

Answer 10

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

Answer 11

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 12

ISNUMERIC will do

Check the NOTES section too in the article.