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module_16_db3/materials/sql_join/join_queries.sql
44 строки
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andrei_shulaev
add materials
01 апр 2021, 12:47
01 апр 2021, 12:47
8475b7c
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-- select * from table_1; -- select * from table_2; -- select * from table_1 inner join table_2 on table_1.first_name = table_2.first_name; -- select table_1.first_name, table_1.last_name, born_city, -- table_2.first_name, table_2.last_name, born_country -- from table_1 -- inner join table_2 -- on table_1.first_name = table_2.first_name; -- select table_1.first_name as t1_first_name, -- table_2.first_name as t2_first_name, -- count(*) as similarities -- from table_1 -- inner join table_2 -- on table_1.first_name = table_2.first_name -- group by table_1.first_name, table_2.first_name -- order by COUNT(table_1.first_name == table_2.first_name) desc; -- select * -- from table_1 -- left outer join table_2 -- on table_1.first_name == table_2.first_name; -- select * -- from table_2 -- left outer join table_1 -- on table_1.first_name == table_2.first_name; -- select * -- from table_1 -- left outer join table_2 -- on table_1.first_name == table_2.first_name -- where table_2.first_name is null; -- select first_name from table_1 -- union -- select first_name from table_2; select first_name from table_1 union all select first_name from table_2;