I m working in MySQL and have to write a select query.
I have related data in four tables. Now, the parent table may have data whose child data may not be present in lower tables.
I want to write a single query to get data from all four tables, irrespective of situation that data is present in child tables or not .
I have tried to write nested select and joins as below, but m not getting the data.
select * from property p where p.Re_ID in
(select Re_id from entry e where e.Re_ID in
(select Re_id from category c where c.Re_ID in
(select id from re)))
Please help me how to get data from all 4 tables.
If cir_registry
is the master, you can select from that and LEFT JOIN
the other tables in the order they're distant from cir_registry
;
SELECT r.ID rId, r.Description rDescription, c.ID cId ...
...
p.Data_Type pDataType
FROM cir_registry r
LEFT JOIN cir_category c ON c.Registry_ID = r.ID
LEFT JOIN cir_entry e ON e.Category_ID = c.ID
LEFT JOIN cir_property p ON p.Entry_IDInSource = e.IDInSource
You should also alias the columns as above, otherwise, for example, p.ID
and c.ID
will both show up in the result set as ID
, and you'll only be able to access one of them.
You might need UNION? Something like:
Select * FROM cir_registry
Union
Select * FROM cir_entry
Union
Select * FROM cir_property
Check the official doc here: http://dev.mysql.com/doc/refman/5.0/en/union.html
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.