There are a few reasons why an Oracle SQL wildcard might not be returning an expected result set. Here are a few of the most common ones:

• The wildcard is not being used correctly. For example, the % wildcard can match zero or more characters, but the _ wildcard can only match a single character.
• The wildcard is being used in the wrong place. For example, the wildcard should be used in the WHERE clause, not the SELECT clause.
• The data that you are trying to match is not in the correct format. For example, if you are trying to match a string that contains spaces, you need to use the ESCAPE character.
• There is a typo in the SQL statement.

To troubleshoot an Oracle SQL wildcard that is not returning an expected result set, you can use the following steps:

1. Check the syntax of the SQL statement. Make sure that you are using the wildcards correctly and that they are in the right place.
2. Check the data that you are trying to match. Make sure that it is in the correct format and that it does not contain any typos.
3. Use the EXPLAIN PLAN command to get a detailed explanation of how the query is being executed. This can help you identify any problems with the query execution plan.
4. Use the tkprof tool to profile the query and identify any performance bottlenecks.

If you are still having trouble troubleshooting the wildcard, you can contact Oracle support for assistance.

Here are some additional tips to help you use Oracle SQL wildcards correctly:

• Use the ESCAPE character to match special characters, such as spaces and quotation marks.
• Use the LIKE operator to specify the wildcard pattern.
• Use the IN operator to match a list of values.
• Use the BETWEEN operator to match a range of values.