"CL" multi-Table query (inner and outer joins)

Cross join: The result set produced by the connection Cartesian product

A has 7 rows, B has 8 rows A of the first row and each row of B to connect, there is 8 A to the first row

7*8=56 Strips

Select A.real_name,s.unix_host,s.os_username

From account a cross join service s; (56)

Select A.real_name,s.unix_host,s.os_username

From account a cross join service s

where a.id = s.account_id;

INNER JOIN (join or INNER join)

Ps:ijoin is a shorthand for the inner join, the same meaning.

Select A.real_name,s.unix_host,s.os_username

From account a join service s on a.id = s.account_id;

Driver table: From this table when generating the result set the left side is the driver table

Match table:

The outer joins are left-connected (either to the right join or to the outer join), to the connection to the starboard join, or to the outer join, and to the full outer join (either the complete join or the outer join)

Left join table with no restrictions

(There are 7 records on the left, of which there are 4 matches on the right with a total of 8, can not find a match to show an entire bar to the right is empty (a total of 3), found matching) Total 11 records

Right join table with no restrictions

(There are 8 records on the right, 8 and 7 on the left have 1 matches, the total 8

"CL" multi-Table query (inner and outer joins)