SHOW DATABASES
The following query is a synonym of the above query.
Both of them list all the databases on the MySQL host:SHOW SCHEMASUniversityDB SHOW TABLES FROM UniversityDBSHOW COLUMNS FROM students
Shortcut of the query above is DESCRIBE DESCRIBE studentsstudents table that is in the university databaseSHOW COLUMNS FROM university.students
Another method to specify a database when listing columns from a tableSHOW COLUMNS FROM students IN universityDESCRIBE students
Note: the query above is alternative and shortcut of SHOW COLUMNS FROM studentsUSE university
For example we can list all columns from any of the table inside the selected database without specifying it.
MySQL will know that we mean already the selected databaseSHOW COLUMNS FROM studentsEXPLAIN provides detailed information about the query result.
One of the information that EXPLAIN gives us is how many rows will be affected after running the queryEXPLAIN UPDATE students SET mail = 'email@gmail.com' WHERE id > 39
Note: EXPLAIN works with the following statements: SELECT, DELETE, INSERT, REPLACE, UPDATEat signs - @.
Shows base directory of MySQLSELECT @@basedir
Shows whether query uses cache or notSELECT @@have_query_cache
Shows what size does query cache haveSELECT @@query_cache_size
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Shows complete list of system variables with their valuesSHOW VARIABLES
Complete list of system variables using phpmyadmin: phpmyadmin/server_variables.php