merge
Creates a temporary Merge table. The table structure is taken from the first table encountered that matches the regular expression.
Syntax
Arguments
- 
db_name— Possible values (optional, default iscurrentDatabase()):- database name,
 - constant expression that returns a string with a database name, for example, 
currentDatabase(), REGEXP(expression), whereexpressionis a regular expression to match the DB names.
 - 
tables_regexp— A regular expression to match the table names in the specified DB or DBs. 
See Also
- Merge table engine