SHOW DATABASES
The following query is a synonym of the above query.
Both of them list all the databases on the MySQL host:SHOW SCHEMAS
UniversityDB
SHOW TABLES FROM UniversityDB
SHOW COLUMNS FROM students
Shortcut of the query above is DESCRIBE
DESCRIBE students
students
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 university
DESCRIBE students
Note: the query above is alternative and shortcut of SHOW COLUMNS FROM students
USE 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 students
EXPLAIN
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
, UPDATE
at 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
...
Shows complete list of system variables with their valuesSHOW VARIABLES
Complete list of system variables using phpmyadmin
: phpmyadmin/server_variables.php