PHP uses mysqli to connect to MySQL database

Connect to MySQL using the Mysqli library, which supports both object-oriented and process-oriented approaches:

1. How to use object-oriented

Establish a connection

$db = new mysqli (' localhost ', ' root ', ' 123456 ', ' dbname ');

Select the database to use if the database is not specified when the connection is established, switch the database used

$db->select_db (' dbname ');

Querying the database

$query = "SELECT * from user WHERE uid=4";

$result = $db->query ($query);

Statistics returns the number of rows in a record

$result _num = $result->num_rows;

Returns a row of results

$row = $result->fetch_assoc (); Returns an associative array that can be obtained by means of the $row[' UID ')

$row = $result->fetch_row (); Returns an array of enumerations, which can be obtained by means of $row[0]

$row = $result->fetch_array (); Returns a mixed array that can be obtained by $row[' uid '] and $row[0] two ways

$row = $result->fetch_object (); Returns an object that can be $row->uid to get a value

Disconnecting database connections

$result->free (); Releasing the result set

$db->close (); Shutting down a database connection is not necessary because the connection is closed automatically when the script finishes executing

Other than that:

Use $db->affected_rows to view the number of rows affected when an INSERT, UPDATE, delete operation occurs

2. Process-oriented usage

Establish a connection

$db = Mysqli_connect (' localhost ', ' root ', ' 123456 ', ' dbname ');

Select the database to use if the database is not specified when the connection is established, switch the database used

mysqli_select_db ($db, ' dbname ');

Querying the database

$query = "SELECT * from user WHERE uid=4";

$result = Mysqli_query ($db, $query);

Statistics returns the number of rows in a record

$result _num = mysqli_num_rows ($result);

Returns a row of results

$row = Mysqli_fetch_assoc ($result); Returns an associative array that can be obtained by means of the $row[' UID ')

$row = Mysqli_fetch_row ($result); Returns an array of enumerations, which can be obtained by means of $row[0]

$row = Mysqli_fetch_array ($result); Returns a mixed array that can be obtained by $row[' uid '] and $row[0] two ways

$row = Mysqli_fetch_object ($result); Returns an object that can be $row->uid to get a value

Disconnecting database connections

Mysqli_free_result ($result); Releasing the result set

Mysqli_close ($DB); Shutting down a database connection is not necessary because the connection is closed automatically when the script finishes executing

Other than that:

Use Mysqli_affected_rows () to view the number of rows affected when an INSERT, UPDATE, delete operation occurs

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