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NO DB CONNECTION: "; echo " $errmsg "; } // SELECT THE MYSQL DATA BASE // MAN PAGE: http://us2.php.net/manual/en/function.mysql-select-db.php if (!$db_sel = mysql_select_db($db_name, $db_connection)) { $errmsg = mysql_errno() . ' ' . mysql_error(); echo "NO DB SELECTION: "; echo " $errmsg "; die('NO DATA BASE'); } // IF WE GOT THIS FAR WE CAN DO QUERIES // ESCAPING A DATA FIELD FOR USE IN MYSQL QUERIES // MAN PAGE: http://us2.php.net/manual/en/function.mysql-real-escape-string.php $safe_username = mysql_real_escape_string($_POST["username"]); // CREATING AND SENDING A SELECT QUERY AND TESTING THE RESULTS // MAN PAGE:http://us2.php.net/manual/en/function.mysql-query.php $sql = "SELECT id FROM my_table WHERE username='$safe_username'"; $res = mysql_query($sql); // IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS // MAN PAGE: http://us.php.net/manual/en/function.mysql-error.php if (!$res) { $errmsg = mysql_errno() . ' ' . mysql_error(); echo "QUERY FAIL: "; echo "$sql "; die($errmsg); } // IF WE GET THIS FAR, THE QUERY SUCCEEDED AND WE HAVE A RESOURCE-ID IN $res SO WE CAN NOW USE $res IN OTHER MYSQL FUNCTIONS // DETERMINE HOW MANY ROWS OF RESULTS WE GOT // MAN PAGE: http://us2.php.net/manual/en/function.mysql-num-rows.php $num = mysql_num_rows($res); if (!$num) { echo "QUERY FOUND NO DATA: "; echo "$sql "; } else { echo "QUERY FOUND $num ROWS OF DATA "; echo "$sql "; } // ITERATE OVER THE RESULTS SET TO SHOW WHAT WE FOUND // MAN PAGE: http://us2.php.net/manual/en/function.mysql-fetch-assoc.php echo "\n"; // MAKE IT EASY TO READ while ($row = mysql_fetch_assoc($res)) { var_dump($row); // MAN PAGE: http://us2.php.net/manual/en/function.var-dump.php } // A WAY OF DETERMINING HOW MANY ROWS WE HAVE IN A TABLE // MAN PAGE: http://us.php.net/mysql_fetch_array $sql = "SELECT COUNT(*) FROM my_table"; $res = mysql_query($sql); // IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS if (!$res) { $errmsg = mysql_errno() . ' ' . mysql_error(); echo "QUERY FAIL: "; echo "$sql "; die($errmsg); } // GET THE RESULTS SET ROW IN AN ARRAY WITH A NUMERIC INDEX - POSITION ZERO IS THE COUNT $row = mysql_fetch_array($res, MYSQL_NUM); $num = $row[0]; // MAKING AN INSERT QUERY AND TESTING THE RESULTS $sql = "INSERT INTO my_table (username) VALUES (\"$safe_username\")"; $res = mysql_query($sql); // IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS if (!$res) { $errmsg = mysql_errno() . ' ' . mysql_error(); echo "QUERY FAIL: "; echo "$sql "; die($errmsg); } // GET THE AUTO_INCREMENT ID OF THE RECORD JUST INSERTED - PER THE DB CONNECTION // MAN PAGE: http://us2.php.net/manual/en/function.mysql-insert-id.php $id = mysql_insert_id($db_connection);
\n"; // MAKE IT EASY TO READ while ($row = mysql_fetch_assoc($res)) { var_dump($row); // MAN PAGE: http://us2.php.net/manual/en/function.var-dump.php } // A WAY OF DETERMINING HOW MANY ROWS WE HAVE IN A TABLE // MAN PAGE: http://us.php.net/mysql_fetch_array $sql = "SELECT COUNT(*) FROM my_table"; $res = mysql_query($sql); // IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS if (!$res) { $errmsg = mysql_errno() . ' ' . mysql_error(); echo "QUERY FAIL: "; echo "$sql "; die($errmsg); } // GET THE RESULTS SET ROW IN AN ARRAY WITH A NUMERIC INDEX - POSITION ZERO IS THE COUNT $row = mysql_fetch_array($res, MYSQL_NUM); $num = $row[0]; // MAKING AN INSERT QUERY AND TESTING THE RESULTS $sql = "INSERT INTO my_table (username) VALUES (\"$safe_username\")"; $res = mysql_query($sql); // IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS if (!$res) { $errmsg = mysql_errno() . ' ' . mysql_error(); echo "QUERY FAIL: "; echo "$sql "; die($errmsg); } // GET THE AUTO_INCREMENT ID OF THE RECORD JUST INSERTED - PER THE DB CONNECTION // MAN PAGE: http://us2.php.net/manual/en/function.mysql-insert-id.php $id = mysql_insert_id($db_connection);