SQLite 如果未达到限制，则从其他表中添加内容

Question

I have a quick question. I have two SQLite tables like the following:

TableOne

id	rowone
1	rowone_content_a
2	rowone_content_ab
3	rowone_content_ac
4	rowone_content_bc

TableTwo

id	rowone	rowtwo
1	rowone_content_a	a
2	rowone_content_ab	ab
3	rowone_content_ac	ac
4	rowone_content_bc	bc

So I want a SQL that has the following behavior:

Search: tent_a (something that contains tent_a somewhere).

When I search for it, I want the following result:

rowname that doesn't matter	from table (not included in the output)
a	TableTwo
ab	TableTwo
ac	TableTwo
rowone_content_a	TableOne
rowone_content_ab	TableOne

Background is that I have a search that should first look in the first row of the second table and select the value of the second row if the value of the first row contains the text I am looking for, limited by 5. But if the data returned from table two is less than 5, the SQL should fill the empty fields with data found in table one.

Thanks for any help.

Answer 1

I think you want union all :

select rowone, 'tableone'
from tableone
where rowone like '%tent\_a%'
union all
select rowtwo, 'tabletwo'
from tabletwo
where rowone like '%tent\_a%'

Answer 2

Use UNION ALL to get all the rows from the 2 tables that satisfy your conditions and then Use ORDER BY and LIMIT to return only the first 5 rows:

SELECT rowname
FROM (
  SELECT rowtwo rowname, 1 fromtable
  FROM TableTwo
  WHERE rowone LIKE '%tent\_a%' ESCAPE '\'
  UNION ALL
  SELECT rowone, 2
  FROM TableOne
  WHERE rowone LIKE '%tent\_a%' ESCAPE '\'
)  
ORDER BY fromtable, rowname LIMIT 5

See the demo .