MySQL inner join on and left join on, innerjoin

MySQL inner join on and left join on, innerjoin

The connection statement used in the WHERE clause is called a recessive connection in the database language. Inner join ...... The connection generated by the ON clause is called an explicit connection.
Inner join: it is interpreted as "valid join". Only data in both tables is displayed as left join. For example, on a. field = B. field,
All data in Table a and all data in Table a \ B are displayed. data in Table A and in Table B is displayed as null. right join: it is interpreted as "right display", for example, on. field = B. field, all data in Table B and all data in Table a \ B are displayed. data in Table B and not in Table A is displayed as null full join: it is interpreted as "full join ", all the data in the two tables is displayed. Actually, the inner (left-inner) (right-inner) completely contains all the records of the two tables.
-- Excerpted from Baidu search.