Microsoft Word - Sam's Teach Yourself MySQL in 21 Days - SAMS.doc

DELETE

[LOW PRIORITY] FROM table_name WHERE conditions [LIMIT n]
The delete command deletes values from a given table based on the conditions expressed in the WHERE
clause. The DELETE statement has the following optional parameters:
ƒ LOW_PRIORITY Delays the deletion until the table is not in use
ƒ LIMIT X Limits the number of deletions to X

Example:

DELETE FROM Customers WHERE Customer_ID = 3

To delete all rows from a table without actually dropping the table, use the following command:

DELETE FROM Customers

DESCRIBE

table_name [column_name]

This statement will show a detailed definition of the columns in a table.

To see a description of all the columns in a table, use the following:

DESCRIBE Customers

To see a description of a specific column, use

DESCRIBE Customers Customer_ID

DROP DATABASE

[IF EXISTS] database_name
The DROP DATABASE statement will delete a database. There are no warnings or questions, so be
careful when you issue this statement.

Example:

DROP DATABASE Meet_A_Geek

DROP FUNCTION

function_name
Deletes a user-defined function from the func table in the mysql database. See CREATE FUNCTION.

DROP INDEX

index_name ON table_name

This statement will delete a given index on a specific table.

Example:

DROP INDEX idx_cust_id ON Customers

DROP TABLE [IF EXISTS]

table_name [, table_name] ...
This statement will delete the specified table. Again, with all DROP and DELETE statements, be careful,
there are no warnings or hesitations.

Example:

DROP TABLE Customers

EXPLAIN

{select_statement or table_name}
This command will display the query plan for the select clause. It displays the same results as the SHOW.
See SHOW.

Example:

EXPLAIN SELECT C.First_Name

FROM Customers AS C, Orders as O

WHERE C.Customer_ID = O.Customer_ID

FLUSH

flush_option[, flush_option] ...

This statement will clear the cache MySQL uses. The possible options are