PHP about MySQL Long connection problem

1, when the function mysql_connect the first three parameters ( server username password）相同，并且第四个参数（new_link）不传递时候，重复调用 mysql_connect will return the same connection.

PHP code

<? PHP $db mysql_connect (' localhost ', ' root ', ' root '); Var_dump ($db); $db 2 mysql_connect (' localhost ', ' root ', ' root '); Var_dump ($db 2); Sleep (10);

Page printing Information

Number of MySQL connections

Mysql> Show Full processlist;+----+------+-----------------+------+---------+------+-------+------------------ -----+| Id | User | Host            | db   | Command | Time | State | Info                  |+----+------+-----------------+------+---------+------+-------+-----------------------+| | root | localhost:54408 | NULL | Query   |    0 | NULL  | show full Processlist | | | | root | localhost:55278 | NULL | Sleep   |    3 |       | NULL                  |+----+------+-----------------+------+---------+------+-------+-----------------------+2 rows in Set

2, when the function mysql_connect passed the fourth parameter ( new_link ), and then repeated calls it.

PHP code

<? PHP $db mysql_connect (' localhost ', ' root ', ' root ', 1); Var_dump ($db); $db 2 mysql_connect (' localhost ', ' root ', ' root ', 1); Var_dump ($db 2); Sleep (10);

Page printing Information

Number of MySQL connections

Mysql> Show Full processlist;+----+------+-----------------+------+---------+------+-------+------------------ -----+| Id | User | Host            | db   | Command | Time | State | Info                  |+----+------+-----------------+------+---------+------+-------+-----------------------+| | root | localhost:54408 | NULL | Query   |    0 | NULL  | show full Processlist | | | | root | localhost:55320 | NULL | Sleep   |    4 |       | NULL                  | | | | root | localhost:55321 | NULL | Sleep   |    4 |       | NULL                  |+----+------+-----------------+------+---------+------+-------+-----------------------+

3. Mysql_pconnect Persistent Connection

PHP code

<? PHP $db Mysql_pconnect (' localhost ', ' root ', ' root '); Var_dump ($db); $db 2 Mysql_pconnect (' localhost ', ' root ', ' root '); Var_dump ($db 2);

Page printing Information

Number of MySQL connections

Mysql> Show Full processlist;+----+------+-----------------+------+---------+------+-------+------------------ -----+| Id | User | Host            | db   | Command | Time | State | Info                  |+----+------+-----------------+------+---------+------+-------+-----------------------+|  1 | Root | localhost:55391 | NULL | Query   |    0 | NULL  | show full Processlist | |  2 | Root | localhost:55393 | NULL | Sleep   |    5 |       | NULL                  |+----+------+-----------------+------+---------+------+-------+-----------------------+

4, Mysql_pconnect plus the fourth parameter (New_link) can establish multiple persistent connections

PHP code

<? PHP $db Mysql_pconnect (' localhost ', ' root ', ' root ', 1); Var_dump ($db); $db 2 Mysql_pconnect (' localhost ', ' root ', ' root ', 1); Var_dump ($db 2);

Page printing Information

Number of MySQL connections

Mysql> Show Full processlist;+----+------+-----------------+------+---------+------+-------+------------------ -----+| Id | User | Host            | db   | Command | Time | State | Info                  |+----+------+-----------------+------+---------+------+-------+-----------------------+|  1 | Root | localhost:55391 | NULL | Query   |    0 | NULL  | show full Processlist | |  2 | Root | localhost:55393 | NULL | Sleep   |  |       | NULL                  | |  3 | Root | localhost:55418 | NULL | Sleep   |    4 |       | NULL                  |+----+------+-----------------+------+---------+------+-------+-----------------------+3 rows in Set

5. Summary:

The persistent connection created by the function mysql_pconnetc after the PHP script ends, the MySQL connection does not end immediately. When it ends, it is managed by MySQL itself. The Mysql_colse function cannot close the MYSQL_PCONNETC connection.

The connection created by the function mysql_connetc will end when the PHP script ends, and the MySQL connection ends accordingly.

PHP about MySQL Long connection problem