whitebear :
I have these tables
One text has many-many items writer,line
ttext_obj table
test obj
1 text1
2 text2
3 text3
4 text4
text_obj_writers table
text writer
1 2
2 3
2 4
text_obj_line table
text line
1 2
4 3
1 4
So, I want to pick up the rows of text_obj which have at reast one writer or one line.
For now I made code like this .
The text_obj id which has at least one write
SELECT text.id FROM `text_obj` text
inner join text_obj_writers writer
on writer.obj_id = text.id group by text.id
//it returns
1
2
The text_obj id which have at least one line
SELECT text.id FROM `text_obj` text
inner join text_obj_lines line
on line.obj_id = text.id group by text.id
//it returns
1
4
But I want to take or of these
1
2
4
How can I concatenate two tables by or ?
Gordon Linoff :
Use exists:
select o.*
from text_obj o
where exists (select 1
from text_obj_writers tow
where tow.obj_id = o.id
) or
exists (select 1
from text_obj_lines tol
where tol.obj_id = o.id
) ;
This is much better than using aggregation, because you do not need to remove duplicates after joining the tables together.
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