SHOW ___ is an odd kind of query which is based off of information in information_schema (a database of meta information).
You might have better luck using a SELECT query directly into information_schema itself; rather than trying to hack your way to an answer.
WHERE TABLE_SCHEMA='your_database_name' //your database name
AND TABLE_NAME LIKE 'some_prefix%';
I use (, ; : -) as I please- instead of learning the English language specification: I decided to learn Scheme and Java;