What is the difference between learning PHP-27th days-connection in the left or right corner with Yan 18?

Difference between learning PHP-27th days-connection in the left or right corner with Yan 18/** & nbsp; Yan 18 public welfare PHP Training & nbsp; classroom address: YY channel 88354001 & nbsp; learning community: www. zixue. it & nbsp; **/mysql & gt; createtableboy (& nbsp; learn the difference between PHP-27th days-connections between the left and right sides
/**
Yan 18 public welfare PHP Training
Classroom address: YY channel 88354001
Learning Community: www. zixue. it
**/




Mysql> create table boy (
-> Bname varchar (20 ),
-> Other char (1)
->) Engine myisam charset utf8;
Query OK, 0 rows affected (0.23 sec)


Mysql>
Mysql> insert into boy
-> Values
-> ('Bloods', 'A '),
-> ('Li Si', 'B '),
-> ('Wang Wu', 'C '),
-> ('Fu Shuai ', 'D '),
-> ('Zheng 7', 'E ');
Query OK, 5 rows affected (0.02 sec)
Records: 5 Duplicates: 0 Warnings: 0


Mysql>
Mysql>
Mysql>
Mysql> create table girl (
-> Gname varchar (20 ),
-> Other char (1)
->) Engine myisam charset utf8;
Query OK, 0 rows affected (0.16 sec)


Mysql>
Mysql> insert into girl
-> Values
-> ('Stewardess ',' B '),
-> ('Big s', 'C '),
-> ('Abaclo', 'D '),
-> ('Cecilia Cheung ', 'D '),
-> ('Lin Daiyu ', 'E '),
-> ('Babywa', 'F ');
Query OK, 6 rows affected (0.03 sec)
Records: 6 Duplicates: 0 Warnings: 0


Mysql> select * from boy;
+ -------- + ------- +
| Bname | other |
+ -------- + ------- +
| Diaosi | A |
| Li Si | B |
| Wang Wu | C |
| Gao fushuai | D |
| Zheng Qi | E |
+ -------- + ------- +
5 rows in set (0.00 sec)


Mysql> select * from girl;
+ -------- + ------- +
| Gname | other |
+ -------- + ------- +
| Flight attendant | B |
| Big s | C |
| Gillian | D |
| Cecilia Cheung | D |
| Lin Daiyu | E |
| Baochai | F |
+ -------- + ------- +
6 rows in set (0.00 sec)


Mysql> select boy. *, girl. * from
-> Boy left join girl on boy. other = girl. other;
+ -------- + ------- +
| Bname | other | gname | other |
+ -------- + ------- +
| Diaosi | A | NULL |
| Li Si | B | flight attendant | B |
| Wang Wu | C | big s | C |
| Gao fushuai | D | a jiao | D |
| Gao fushuai | D | Cecilia Cheung | D |
| Zheng Qi | E | Lin Daiyu | E |
+ -------- + ------- +
6 rows in set (0.00 sec)


Mysql> # When a girl comes on stage, the other half is taken, and the other half is left blank.
Mysql> select boy. *, girl. * from
-> Girl left join boy on boy. other = girl. other;
+ -------- + ------- +
| Bname | other | gname | other |
+ -------- + ------- +
| Li Si | B | flight attendant | B |
| Wang Wu | C | big s | C |
| Gao fushuai | D | a jiao | D |
| Gao fushuai | D | Cecilia Cheung | D |
| Zheng Qi | E | Lin Daiyu | E |
| NULL | Baochai | F |
+ -------- + ------- +
6 rows in set (0.00 sec)


Mysql> # Note: a left join B does not mean that table a must be on the left, but that table a prevails when querying data.
Mysql> select * from boy;
+ -------- + ------- +
| Bname | other |
+ -------- + ------- +
| Diaosi | A |
| Li Si | B |
| Wang Wu | C |
| Gao fushuai | D |
| Zheng Qi | E |
+ -------- + ------- +
5 rows in set (0.00 sec)


Mysql> select other, bname from boy;
+ ------- + -------- +
| Other | bname |
+ ------- + -------- +
| A | diaosi |
| B | Li Si |
| C | Wang Wu |
| D | Gao fushuai |
| E | Zheng Qi |
+ ------- + -------- +
5 rows in set (0.00 sec)


Mysql> # When a girl comes on stage, the other half is taken, and the other half is left blank.
Mysql> # Do not use left join
Mysql> # Use Right join. it was just a girl left join male.
Mysql> # connect with the right, just right join male
Mysql> select boy. *, girl .*
-> From
-> Boy right join girl
-> On boy. other = girl. other;
+ -------- + ------- +
| Bname | other | gname | other |
+ -------- + ------- +
| Li Si | B | flight attendant | B |
| Wang Wu | C | big s | C |
| Gao fushuai | D | a jiao | D |
| Gao fushuai | D | Cecilia Cheung | D |
| Zheng Qi | E | Lin Daiyu | E |
| NULL | Baochai | F |
+ -------- + ------- +
6 rows in set (0.01 sec)


Mysql> select boy. *, girl .*
-> From
-> Boy inner join girl
-> On boy. other = girl. other;
+ -------- + ------- +
| Bname | other | gname | other |
+ -------- + ------- +
| Li Si | B | flight attendant | B |
| Wang Wu | C | big s | C |
| Gao fushuai | D | a jiao | D |
| Gao fushuai | D | Cecilia Cheung | D |
| Zheng Qi | E | Lin Daiyu | E |
+ -------- + ------- +
5 rows in set (0.00 sec)


Mysql> exit




Instructor Yan Shiba is too humorous. yesterday's video is as follows:

Http://www.tudou.com/programs/view/TVhY20adVL4/