Other functions : PHP

int mysql_change_user(string user, string password, [string database, [resource connection]])

Changes the logged-in MySQL user to another user, using that user's password for an optionally specified database and connection. If omitted, the current database and most recently opened connection are assumed. Returns false on failure and, if it does fail, the previous, successful connection stays current.

int mysql_create_db(string db, [resource connection])

Creates a database named db using the connection resource returned from a mysql_connect( ) function call or the last-opened connection if the parameter is omitted.

int mysql_drop_db(string db, [resource connection])

Drops a database named db using the connection resource returned from a mysql_connect( ) function call or the last-opened connection if the parameter is omitted.

object mysql_fetch_field(resource result_set, [int attribute_number])

Returns as an object the metadata for each attribute associated with a result_set resource returned from a query function call. An optional attribute_number can be specified to retrieve the metadata associated with a specific attribute. However, repeated calls process the attributes one by one.

The properties of the object returned by the function are:

name: The attribute name
table: The name of the table that the attribute belongs to
max_length: The maximum length of the attribute
not_null: Set to 1 if the attribute can't be NULL
primary_key: Set to 1 if the attribute forms part of a primary key
unique_key: Set to 1 if the attribute is a unique key
multiple_key: Set to 1 if the attribute is a nonunique key
numeric: Set to 1 if the attribute is a numeric type
blob: Set to 1 if the attribute is a BLOB type
type: The type of the attribute
unsigned: Set to 1 if the attribute is an unsigned numeric type
zerofill: Set to 1 if the numeric column is zero-filled

Example 4-3 is a script that uses the mysql_fetch_field() function to emulate most of the behavior of the SHOW COLUMNS or DESCRIBE commands discussed in Chapter 3. The code uses the same five-step query process discussed earlier, with the exception that mysql_fetch_field( ) is used in place of mysql_fetch_row( ). Sample output for the table wine is shown in Example 4-4. The same result could have been achieved by executing DESCRIBE WINE on the winestore database using mysql_query( ) and retrieving the results with mysql_fetch_object( ).

This function also has other uses. For example, it can be used in validation-the subject of Chapter 7-to check whether the data entered by a user is longer than the maximum length of the database attribute. Indeed, a script can be developed that automatically performs basic validation based on the table structure.