The EXPLAIN statement can be used either as a synonym for
DESCRIBE or as a way to obtain information about how MySQL will execute
a SELECT statement:

 --- The EXPLAIN tbl_name syntax is synonymous with DESCRIBE tbl_name
or
SHOW COLUMNS FROM tbl_name.
 --- When you precede a SELECT statement with the keyword EXPLAIN,
MySQL explains how it would process the SELECT, providing
information about how tables are joined and in which order.
