General steps for php to access mysql database

PHP access operationMySQL 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 based on the connection identifier returned in the first step. Select the database

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

3. Use the mysql_query() function to execute the SQL statement

The first step: mysql_query("select * from tb_stu", $connID); //Execute the query and return the result set

Step 2: Obtain information from the above result set. There are two paths here. 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 operations on data:

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 the resources

mysql_free_result($result);

5. Close the mysql server connection

Every time you use the mysql_connect() or mysql_query() function, system resources will be consumed. To avoid wasting resources, use mysql_close () function closes the connection to the MySQL server to save system resources.

mysql_close($connID);

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