Описание тега isnumeric

Syntax

ISNUMERIC ( expression )

Remarks

ISNUMERIC returns 1 when the input expression evaluates to a valid numeric data type; otherwise it returns 0. Valid numeric data types include the following:

https://stackru.com/images/46c0596001a6302c793a721cb2172a9c9b8b14e7.png

Example

USE AdventureWorks2012;
GO
SELECT City, PostalCode
FROM Person.Address 
WHERE ISNUMERIC(PostalCode)<> 1;
GO

Note

For, SQL Server 2012+ use TRY_PARSE instead as ISNUMERIC is treating as numbers some not numeric values:

SELECT ISNUMERIC('123') as '123'
      ,ISNUMERIC('abc') as 'abc'
      ,ISNUMERIC('-') as '-'
      ,ISNUMERIC('+') as '+'
      ,ISNUMERIC('$') as '$'
      ,ISNUMERIC('.') as '.'
      ,ISNUMERIC(',') as ','
      ,ISNUMERIC('\') as '\'

https://stackru.com/images/d86c705f5f81e9f70ff65ab7957f1e56d246178b.png

More details can be found here