How to Optimize Queries for Comma-Separated Columns in Databases?

Optimizing Queries for Comma-Separated Columns

Database tables often contain columns with comma-separated lists of values, creating challenges when querying for specific values. Consider a table with a "CATEGORIES" column in the following format:

ID | CATEGORIES
---------------
1  | c1
2  | c2,c3
3  | c3,c2
4  | c3
5  | c4,c8,c5,c100

To search for specific categories, you may initially opt for LIKE statements:

SELECT id FROM table WHERE categories LIKE '%c2%'; -- Returns rows 2 and 3

However, LIKE statements can be inefficient for comma-separated columns. Oracle's FIND_IN_SET() function may seem like a suitable alternative, but it is not available in Oracle 10g.

A more optimal approach is to use LIKE with appropriate wildcards:

SELECT 
  * 
FROM
  YourTable 
WHERE 
  ',' || CommaSeparatedValueColumn || ',' LIKE '%,SearchValue,%'

This query adds commas around the search value to ensure exact matches. However, it can still be slow due to the use of LIKE.

A superior solution is to restructure the data into separate tables with cross-linking to avoid the limitations of comma-separated columns, significantly improving query performance.

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