لطفا منتظر باشید ...
"Getting Started with MySQL", we connected to the MySQL
database server using a program called mysql that allowed
us to type SQL queries (commands) and view the results of those queries immediately.
In PHP, a similar mechanism exists: the mysql_query function.
mysql_query(query, connection_id);
Here query is a string that contains the
SQL command we want to execute. As with mysql_select_db,
the connection identifier parameter is optional.
What this function returns will depend on the type of query being sent.
For most SQL commands, mysql_query returns either true
or false to indicate success or failure respectively. Consider the following
example, which attempts to create the Jokes table
we created in "Getting Started with MySQL":
$sql = 'CREATE TABLE Jokes (
ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
JokeText TEXT,
JokeDate DATE NOT NULL
)';
if ( @mysql_query($sql) ) {
echo('<p>Jokes table successfully created!</p>');
} else {
die('<p>Error creating Jokes table: ' .
mysql_error() . '</p>');
}
Again, we use the @ trick to suppress any error messages
produced by mysql_query, and instead print out a friendlier
error message of our own. The mysql_error function used
here returns a string of text that describes the last error message that was
sent by the MySQL server.
For DELETE, INSERT, and UPDATE queries (which serve to
modify stored data), MySQL also keeps track of the number of table rows (entries)
that were affected by the query. Consider the SQL command below, which we
used in "Getting Started with MySQL" to set the dates of all
jokes that contained the word "chicken":
$sql = "UPDATE Jokes SET JokeDate='1990-04-01'
WHERE JokeText LIKE '%chicken%'";
When we execute this query, we can use the mysql_affected_rows function
to view the number of rows that were affected by this update:
if ( @mysql_query($sql) ) {
echo('<p>Update affected ' . mysql_affected_rows() .
' rows.</p>');
} else {
die('<p>Error performing update: ' . mysql_error() .
'</p>');
}SELECT queries are treated a little differently,
since they can retrieve a lot of data, and PHP must provide ways to handle
that information.
