Using LIKE in an Oracle IN clause

Question

I know I can write a query that will return all rows that contain any number of values in a given column, like so:

Select * from tbl where my_col in (val1, val2, val3,... valn)

but if val1, for example, can appear anywhere in my_col, which has datatype varchar(300), I might instead write:

select * from tbl where my_col LIKE '%val1%'

Is there a way of combing these two techniques. I need to search for some 30 possible values that may appear anywhere in the free-form text of the column.

Combining these two statements in the following ways does not seem to work:

select * from tbl where my_col LIKE ('%val1%', '%val2%', 'val3%',....) 

select * from tbl where my_col in ('%val1%', '%val2%', 'val3%',....)

Answer 1

I prefer this

WHERE CASE WHEN my_col LIKE '%val1%' THEN 1    
           WHEN my_col LIKE '%val2%' THEN 1
           WHEN my_col LIKE '%val3%' THEN 1
           ELSE 0
           END = 1

I'm not saying it's optimal but it works and it's easily understood. Most of my queries are adhoc used once so performance is generally not an issue for me.

Answer 2

A REGEXP_LIKE will do a case-insensitive regexp search.

select * from Users where Regexp_Like (User_Name, 'karl|anders|leif','i')

This will be executed as a full table scan - just as the LIKE or solution, so the performance will be really bad if the table is not small. If it's not used often at all, it might be ok.

If you need some kind of performance, you will need Oracle Text (or some external indexer).

To get substring indexing with Oracle Text you will need a CONTEXT index. It's a bit involved as it's made for indexing large documents and text using a lot of smarts. If you have particular needs, such as substring searches in numbers and all words (including "the" "an" "a", spaces, etc) , you need to create custom lexers to remove some of the smart stuff...

If you insert a lot of data, Oracle Text will not make things faster, especially if you need the index to be updated within the transactions and not periodically.