CODEWITHSUNDEEP
sqlpostgresql
Sergey Kozlov
Sergey Kozlov

Reputation: 452

PostgreSQL query with the data from the references table

I have two tables:

items

------------------
| item_id | text |
------------------

CREATE TABLE items (
item_id varchar PRIMARY KEY,
text varchar
);

activity

------------------------
| message_id | item_id |
------------------------

CREATE TABLE activity (
message_id varchar PRIMARY KEY,
item_id varchar not null references items(item_id)
);

How to correctly make a query with the data from the items table? I need to find by value message_id or item_id

I tried:

select * from items, activity where items.item_id = activity.item_id and activity.item_id = 'it123';

select * from activity, items where activity.item_id = items.item_id and 'activity.item_id' = 'it123';

This true query:

SELECT * FROM items JOIN activity ON items.item_id = activity.item_id;

And this true query:

SELECT * FROM activity WHERE item_id = 'ea02ea57ff1b';

Upvotes: 0

Views: 1018

Answers (1)

Dr G.
Dr G.

Reputation: 1332

You need a table JOIN. So you could do something like:

SELECT * FROM items 
   JOIN activity ON items.item_id = activity.item_id
   WHERE items.item_id = 'it123';

Upvotes: 1

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