MySQL_Table_Join_Query

摘要: Internal connection -- No connection -- Where = -- Abbreviation -- External connection -- Multi condition (and)

1. Internal connection

i. No connection

select * from t_book, t_bookType;

ii. Where =

select bookName, author, bookTypeName  from t_book, t_bookType where t_book.bookTypeId = t_bookType.id;

iii. Abbreviation

select tb.bookName, tb.author, tbt.bookTypeName  from t_book tb, t_bookType tbt where tb.bookTypeId = tbt.id;

2. External connection

Be careful: left join --> all information of first table

right join --> all information of second table

select * from t_book tb left join t_bookType tbt on tb.bookTypeId = tbt.id;
select * from t_book tb right join t_bookType tbt on tb.bookTypeId = tbt.id;

3. Multi condition --> and

select tb.bookName, tb.author, tb.price, tbt.bookTypeName  from t_book tb, t_bookType tbt where tb.bookTypeId = tbt.id and tb.price>70;