PHP database programming---mysql extension library

1, Java has a way to operate the database, PHP has three ways to operate the MySQL database. (1) MySQL extension library; (2) Mysqli extension Library; (3) PDO;

2, MySQL extension library and MySQL database differences

3, three-layer structure of MySQL database

4, MySQL extension library is a bunch of functions that PHP designers provide to programmers to complete various operations (CRUD) on the MySQL database. Use PHP's MySQL extension library to complete the case of MySQL operations: write a program that reads data from the User1 table and prints it in a Web page.

(1) Environment construction

① enable MySQL extension library, configure the MySQL extension library in the php.ini file, Extension=php_mysql.dll. You can <?php phpinfo ()?> See what extension libraries are currently supported by PHP.

② Create a user table that inserts data into the table for use by the program.

(2) write the PHP program, complete the display of the user table.

$conn = mysql_connect ("10.3.255.21", "Liuhuayong", "AWMY6HQLF", "3400"), if (! $conn) {die    ("Connection Failed". Mysql_error ());} 2. Select Database mysql_select_db ("test");//3. Set operation code (recommended) mysql_query ("Set names UTF8")//4. Send instruction SQL (DDL data definition language, such as creating tables, DML data manipulation language, which is the INSERT, UPDATE, DELETE,DQL data Query Language, is a SELECT,DTL data transaction statement, such as rollback commit. $sql = "SELECT * from  liuhuayongblog"; $res = mysql_query ($sql, $conn);//5. Receives the returned result and processes while ($row = Mysql_fetch_row ( $res)) {    var_dump ($row);} 6. Release the resources, close the connection, the database imports the data in memory Mysql_free_result ($res);//This sentence can not, recommend this mysql_close ($conn);

5, details

(1) After using the $res result set, the resources must be released in time.

(2) If there is no mysql_close (), the system will turn off automatically.

(3) Finish $res = mysql_query($sql, $conn), close the connection mysql_close($conn) directly, and have no effect on the program because the $ Res points to the appropriate resource in memory (database data is imported into memory) and does not require a database. This is not the same as Java.

(4) In addition to Mysql_fetch_row ($res), there are three ways to obtain data from $res, respectively:

①mysql_fetch_row ($res), returns an array of indexes;

②MYSQL_FETCH_ASSOC ($res), returns an associative array;

③mysql_fetch_array ($res), returns an indexed array and an associative array (two sets);

④mysql_fetch_object ($res), returns a row of data as an object

6, when the database is modified, the same process and query, using $res = Mysql_execute ($sql, $conn), just change the $sql statement.

PHP database programming---mysql extension library