Finding rows that don't contain numeric data in Oracle

Question

I am trying to locate some problematic records in a very large Oracle table. The column should contain all numeric data even though it is a varchar2 column. I need to find

Answer 1

Use this

SELECT * 
FROM TableToSearch 
WHERE NOT REGEXP_LIKE(ColumnToSearch, '^-?[0-9]+(\.[0-9]+)?$');

Answer 2

I was thinking you could use a regexp_like condition and use the regular expression to find any non-numerics. I hope this might help?!

SELECT * FROM table_with_column_to_search WHERE REGEXP_LIKE(varchar_col_with_non_numerics, '[^0-9]+');

Answer 3

After doing some testing, building upon the suggestions in the previous answers, there seem to be two usable solutions.

Method 1 is fastest, but less powerful in terms of matching more complex patterns.
Method 2 is more flexible, but slower.

Method 1 - fastest
I've tested this method on a table with 1 million rows.
It seems to be 3.8 times faster than the regex solutions.
The 0-replacement solves the issue that 0 is mapped to a space, and does not seem to slow down the query.

SELECT *
FROM <table>
WHERE TRANSLATE(replace(<char_column>,'0',''),'0123456789',' ') IS NOT NULL;

Method 2 - slower, but more flexible
I've compared the speed of putting the negation inside or outside the regex statement. Both are equally slower than the translate-solution. As a result, @ciuly's approach seems most sensible when using regex.

SELECT *
FROM <table>
WHERE NOT REGEXP_LIKE(<char_column>, '^[0-9]+$');

Answer 4

You can use this one check:

create or replace function to_n(c varchar2) return number is
begin return to_number(c);
exception when others then return -123456;
end;

select id, n from t where to_n(n) = -123456;

Answer 5

From http://www.dba-oracle.com/t_isnumeric.htm

LENGTH(TRIM(TRANSLATE(, ' +-.0123456789', ' '))) is null

If there is anything left in the string after the TRIM it must be non-numeric characters.

Answer 6

After doing some testing, i came up with this solution, let me know in case it helps.

Add this below 2 conditions in your query and it will find the records which don't contain numeric data

 and REGEXP_LIKE(<column_name>, '\D') -- this selects non numeric data
 and not REGEXP_LIKE(column_name,'^[-]{1}\d{1}') -- this filters out negative(-) values