MySQL: Dropping specific tables from a schema if tablename not found?

Question

I have a information schema of tables, say it contains

aaaa_tale
bbbb_table
cccc_table
dddd_table

I have another table that contains a list of table names.

cccc_table
bbbb_table

Is there a command I can execute that will allow me to drop the tables in the schema that are not found in the table containing table names? So afterwards only aaaa_table and dddd_table are left in the schema.

Answer 1

Assuming the table that has the list of tables not to be dropped is named "table_list" with the list in a "table_name" column. If you want to use pure SQL, you can do one of these depending on what tables you want to retain in the schema (not clear from your question):

Case: You want to drop the tables listed in the list of tables, so that only aaaa_table and dddd_table remain (refer to the last sentence of your question).

SET GROUP_CONCAT_MAX_LEN=10000; /* Adjust this as per your requirement */
SELECT CONCAT( 'DROP TABLE ',
GROUP_CONCAT(TABLE_NAME) ) INTO @drop_query
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = database()  
AND TABLE_NAME IN (SELECT table_name from table_list);
SET @drop_query = IFNULL(@drop_query, 'SELECT 1'); 
PREPARE drop_statement FROM  @drop_query;
SET foreign_key_checks = 0;
EXECUTE drop_statement;
SET foreign_key_checks = 1;
DEALLOCATE PREPARE drop_statement;

Case: You want to retain the tables listed in the list of tables, so that only cccc_table and dddd_table remain (refer to the second-last sentence of your question, especially "allow me to drop the tables in the schema that are NOT found in the table containing table names").

SET GROUP_CONCAT_MAX_LEN=10000; /* Adjust this as per your requirement */
SELECT CONCAT( 'DROP TABLE ',
GROUP_CONCAT(TABLE_NAME) ) INTO @drop_query
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = database()  
AND TABLE_NAME NOT IN (SELECT table_name from table_list);
SET @drop_query = IFNULL(@drop_query, 'SELECT 1'); 
PREPARE drop_statement FROM  @drop_query;
SET foreign_key_checks = 0;
EXECUTE drop_statement;
SET foreign_key_checks = 1;
DEALLOCATE PREPARE drop_statement;

In both cases, you can avoid the hack to check for NULL and if found, substitute with a dummy query ("SELECT 1") in the above code by using a stored procedure. A stored procedure will allow you to execute a conditional block only if @drop_query is not NULL.