5 steps to operate MySQL database with PHP

PHP operating MySQL database can generally be divided into 5 steps: 1. Connect to the MySQL database server; 2. Select the database; 3. Execute the SQL statement; 4. Close the result set; 5. Disconnect from the MySQL database server.

1. Use the mysql_connect() function to connect to the MySQL database server

Use the mysql_connect() function to establish a connection with the server. Different connections are then positioned based on the return value of this function.

$host = "localhost"; //MySQL服务器地址
$user = "root"; //用户名
$pwd = "***"; // 密码
$connID = mysql_connect($host, $user,$pwd); //返回的连接标识符

2. Use the mysql_select_db() function to select the database file

Use the mysql_select_db() function to select the database based on the connection identifier returned in the first step

mysql_select_db($dbName,$connID); //$dbName 表示要选择的数据库

3. Use The mysql_query() function executes the SQL statement

Step one:

mysql_query("select * from tb_stu",$connID); //执行查询 返回结果集

Step two: Obtain information from the above result set. There are two paths. 1. Use the mysql_fetch_array() function to obtain information from the array result set; 2. Use the mysql_fetch_object() function to obtain a row from the result set as an object. The difference between them is that the return value of mysql_fetch_object() is an object, not an array, that is, the function can only access the array through the field name.

$result = mysql_fetch_array($query);

OR

$result = mysql_fetch_object($query);

There are generally five types of data operations:

1. Query data (select)

2. Display data (select)

3.Insert data(insert)

4.Update data(update)

5.Delete data(delete)

4.Close the result set

After the database operation is completed, you need to close the result set and release resources

mysql_free_result($result);

5. Disconnect the server connection

Every time you use the mysql_connect() or mysql_query() function, it will Consumes system resources. To avoid wasting resources, use the mysql_close() function to close the connection with the MySQL server to save system resources.

mysql_close($connID);