Select max int from varchar column

Question

I am trying to retrieve the largest number from a varchar column that includes both numbers and strings. An example of the data I\'m working with:

BoxNumber

Answer 1

SELECT MAX(CAST(value as signed)) FROM yourTable
WHERE VALUE NOT LIKE '%[a-z]%'
AND ISNUMERIC(VALUE) = 1

In MySql

You should use signed instead of int to cast correctly.

P.s types used to cast may differ in MySql

For more conversions visit this link

Answer 2

you need a combination because of the fact that isnumeric returns 1 for the following things

select isnumeric('+'),isnumeric('5d2') 

your where clause would be like this

WHERE VALUE NOT LIKE '%[a-z]%'
        AND ISNUMERIC(VALUE) = 1

create table #bla (value varchar(50))
insert #bla values('123')
insert #bla values('a5')
insert #bla values('789')
insert #bla values('b1')

SELECT MAX(CAST(value AS Int)) FROM #bla
WHERE VALUE NOT LIKE '%[a-z]%'
    AND ISNUMERIC(VALUE) = 1

I wrote about this here ISNUMERIC Trouble

Answer 3

Well, in the intervening 11 years since this question was asked, SQL Server gained the try_cast function, which returns null rather than throwing an error if the conversion doesn't succeed. So in current versions of SQL Server, a valid answer is

select max(try_cast(BoxNumber as int)) from theTable