tailieunhanh - Mysql your visual blueprint for creating open source databases- P2

Mysql your visual blueprint for creating open source databases- P2:The show tables command displays a list of tables available in the currently selected database. You can use this command when you are unsure of the exact name of a table within the database. | INTRODUCING MYSQL M SHOW TABLES DELETE The SHOW TABLES command displays a list of tables available in the currently selected database. You can use this command when you are unsure of the exact name of a table within the database. Example SHOW TABLES The DELETE command deletes one or more rows of data within an existing table. The WHERE clause should be used to specify the rows that will be deleted. Use this command with care If you omit the WHERE clause all rows of data within the table are deleted. See Chapter 4 for further information about the DELETE command. Example DELETE FROM address WHERE name John Smith INSERT The INSERT command inserts a new row of data into an existing table within the currently selected database. You can specify a list of fields in the INSERT command along with values for each field. The INSERT command is described in detail in Chapter 4. Example INSERT INTO address name address phone VALUES John Smith 321 Elm Street 804-555-1234 UPDATE SELECT The SELECT command retrieves one or more rows from a database. You can specify the columns to be returned or use the wildcard to return values for all columns in the order they appear in the table definition. You can use a WHERE clause to specify one or more conditions that rows must match in order to be returned. If you do not use a WHERE clause the specified columns from all of the rows in the database are returned. Example SELECT name address phone FROM address WHERE name like Smith The UPDATE command alters one or more existing rows of data within a table. The WHERE keyword can be used with this command to specify one or more rows to alter. The command specifies new values for one or more of the fields within each row. These values can be based on existing fields or constant values specified within the command. If you do not specify a WHERE clause this command will update all of the rows in the table. While you will sometimes want to update all of the rows using UPDATE without a WHERE clause .