I have two tables:

'post' table:
[post_id,name_id,name,text]
1,NULL,Steve,My post
2,1,NULL,Second text

'name' table:
[name_id,name]
1,John
2,Eve

I need to get:
[post_id,name,text]
1,Steve,My post
2,John,Second text

With
SELECT * FROM post p LEFT JOIN name n ON p.name_id = n.name_id
I'm loosing data from table 'post'.

I'm new to SQL so please help me.

Krzyc

Because you have the same col name in your tables

try to use

select
p.post_id,p.name_id,p.name,p.text,
n.name_id,n.name
from
post p LEFT JOIN name n ON p.name_id = n.name_id

Thanks omiossec, but your code
returns:

[post_id,name_id,name,text]
1,NULL,NULL,My post <- NULL value because of NULL row id
2,1,John,Second text

Maybe it is a result of calling MySQL from PHP and reading with mysql_fetch_array? I realise that I can use something like this
but with many fields this query will be very very long. I don't know how it will affect execution time.

which value do you need (a from which tables) ?

If there is 'name_id' in table 'post' then I need 'name' from 'name' table. Otherwise I need 'name' value from 'post' table.

It will be best if I can link 'name' table to 'post' table only if there is not null 'name_id' in 'post' table - but AFAIK it is not possible.

(I used these tables only for explanation - my real tables are much more complicated and that is reason why I am searching for best solution.)

SELECT p.post_id, p.name_id, COALESCE(n.name,p.name), p.text
FROM post p LEFT JOIN name n ON p.name_id = n.name_id