1.innerjoin（内连接,或等值连接）select * from table1 inner join table2 on table1.column1= table2.column2;2.lef
1.innerjoin（内连接,或等值连接）
select * from table1 inner join table2 on table1.column1= table2.column2;2.left join（左连接）
select * from table1left join table2 on table1.column1= table2.column2;3.right join（右连接）
select * from table1 right join table2 on table1.column1= table2.column2;4.select并集
select * from table1left join table2 on table1.column1= table2.column2 union select * from table1 right join table2 on table1.column1= table2.column2;