[sql] sql like operator to get the numbers only

This is I think a simple problem but not getting the solution yet. I would like to get the valid numbers only from a column as explained here.

Lets say we have a varchar column with following values

ABC
Italy
Apple
234.62
2:234:43:22
France
6435.23
2
Lions

Here the problem is to select numbers only

select * from tbl where answer like '%[0-9]%' would have done it but it returns

    234.62
    2:234:43:22
    6435.23
    2

Here, obviously, 2:234:43:22 is not desired as it is not valid number.

The desired result is

        234.62
        6435.23
        2

Is there a way to do this?

Try something like this - it works for the cases you have mentioned.

select * from tbl
where answer like '%[0-9]%'
and answer not like '%[:]%'
and answer not like '%[A-Z]%'

You can use the following to only include valid characters:

SQL

SELECT * FROM @Table
WHERE Col NOT LIKE '%[^0-9.]%'

Results

Col
---------
234.62
6435.23
2

what might get you where you want in plain SQL92:

select * from tbl where lower(answer) = upper(answer)

or, if you also want to be robust for leading/trailing spaces:

select * from tbl where lower(answer) = trim(upper(answer))

With SQL 2012 and later, you could use TRY_CAST/TRY_CONVERT to try converting to a numeric type, e.g. TRY_CAST(answer AS float) IS NOT NULL -- note though that this will match scientific notation too (1+E34). (If you use decimal, then scientific notation won't match)