SELECT * FROM table1, table2, table3

Question

I have a problem ... In table1 I have an id, I have to compare that id in table2, then fetch the second id that is in table2 and compare it to table3 and get as a result a datum. Example

TABLE1
ID   NAME ECC...
1      Jhon
2      Frank

TABLE2
ID ID2 ECC..
1   4
2   8

TABLE3
ID NAME
4    Sea
8    Hello

If I look for id 1, the result must be Sea If I look for id 2 the result must be Hello

Thanks!

you tagged 3 different flavors of SQL... which is it? The answer is a `INNER JOIN`... just research this — S3S, Jun 13 '17 at 13:11
This question's causing a lot of friction. Plus, the RDBMS is unknown. MySQL and MSSQL are two different animals; you should tag accordingly. There's also no "php" here. — Funk Forty Niner, Jun 13 '17 at 13:43

score 1 · Answer 1 · answered Jun 13 '17 at 13:14

1

 SELECT Table3.NAME
   FROM Table1
  INNER JOIN Table2
 ON Table1.ID = Table2.ID
  INNER JOIN Table3
 ON Table3.ID = Table2.ID2
  WHERE Table1.ID = 1  -- Your Search here

answered Jun 13 '17 at 13:14

Esteban P.

2,789
2
27
43

score 0 · Accepted Answer · answered Jun 13 '17 at 13:15

0

You should use joins.

Your query will look like :

SELECT t3.name
FROM table3 t3
LEFT JOIN table2 t2 ON t3.id = t2.id2
LEFT JOIN table1 t1 ON t2.id2 = t1.id
WHERE t1.id = <your_number>

answered Jun 13 '17 at 13:15

Iksen

24
2

Thanks!! Very functional method!! – falco3205 Jun 14 '17 at 00:12

Gauravk · Answer 3 · 2017-06-13T19:23:40.540

-1

Query:

 SELECT a.name As Name FROM table3 a JOIN 
 (SELECT b.id2 AS id FROM table1 a JOIN table2 b ON a.id = b.id)b
 ON a.id = b.id where b.id = <your id number (1,2) Anything>

edited Jun 13 '17 at 19:23

answered Jun 13 '17 at 13:17

Gauravk

49
4

a very odd way to approach this.... – S3S Jun 13 '17 at 13:18
It approach is much better than to join 3 table in a query. – Gauravk Jun 13 '17 at 13:22
Why is it better? And you are joining 3 tables. – HoneyBadger Jun 13 '17 at 13:23
you are saying your subquery has benefits over explicit joins? Please, explain... I'm sure we'd all be interested in hearing your arguements – S3S Jun 13 '17 at 13:23
As per my view it would be the faster than explicit joins. – Gauravk Jun 13 '17 at 13:27
1

Your "view" is wrong. – S3S Jun 13 '17 at 13:27
@Gauravk subselects are rarely a better approach than joins, normally they're a lot less efficient; and a lot less readable in this case too – Mark Baker Jun 13 '17 at 13:27
Ok got it, Thanks scsimon , @Mark Baker – Gauravk Jun 13 '17 at 13:31

score -1 · Answer 4 · answered Jun 13 '17 at 13:24

-1

select Table2.Id,Table3.Name from Table1 inner join Table2 on Table2.ID2 = Table3.Id

answered Jun 13 '17 at 13:24

Nithin

1,376
12
29

You're missing a join on Table3. This query will fail. – S3S Jun 13 '17 at 13:25
1

sorry select Table2.Id,Table3.Name from Table2 inner join Table3 on Table2.ID2 = Table3.Id try this – Nithin Jun 14 '17 at 04:20

score -2 · Answer 5 · answered Jun 13 '17 at 13:13

-2

Should be something like this:

select table3.name as name3
from table3
where table3.ID = table2.ID2
and table2.ID = table1.ID
and table1.ID = <YOURNUMBERHERE>

answered Jun 13 '17 at 13:13

Paladin

1,637
13
28

3

you're missing a few joins here.... – S3S Jun 13 '17 at 13:13
@scsimon doing some implicit joins with where-and combinations, one can also perform this with LEFT JOIN and so on, but it wrote it out of my head, so no joins ;) But you are right, JOIN would be the best way – Paladin Jun 13 '17 at 13:15
No, there are no implicit joins here, `table2` and `table1` are not mentioned in the `from` clause – HoneyBadger Jun 13 '17 at 13:16

SELECT * FROM table1, table2, table3

5 Answers5