How do I get information from multiple MySQL tables? - mysql

Question

I'm working on a way to keep track of physical connections between servers/switches in multiple racks. I set up my database so it is like this:
mysql> show tables;
+----------------------+
| Tables_in_System |
+----------------------+
| connections |
| racks |
| servers |
+----------------------+
mysql> select * from racks;
+----+-------------+-------------+----------+
| id | rack_number | rack_height | location |
+----+-------------+-------------+----------+
| 2 | 7430 | 43 | xxx |
| 3 | 7431 | 43 | xxx |
| 4 | 7432 | 43 | xxx |
+----+-------------+-------------+----------+
mysql> select * from servers;
+----+-------------+---------------+-----------------+---------------+
| id | server_type | rack_location | server_unit_loc | server_height |
+----+-------------+---------------+-----------------+---------------+
| 1 | Server 1 | 7430 | 2 | 3 |
| 2 | Cisco 2960 | 7431 | 1 | 1 |
| 3 | Server 2 | 7431 | 9 | 1 |
| 15 | Server 3 | 7432 | 27 | 2 |
| 16 | Cisco 2248 | 7432 | 29 | 1 |
+----+-------------+---------------+-----------------+---------------+
rack_location refers to the numbered racks in the first table.
server_unit_loc is the placement of the server in the rack, 1 being the top, 43 would be the bottom. And server_height is just how tall the server is.
mysql> select * from connections;
+----+----------+----------+------------+------------+---------+---------+------------+
| id | rack_id1 | rack_id2 | server_id1 | server_id2 | port_s1 | port_s2 | cable_type |
+----+----------+----------+------------+------------+---------+---------+------------+
| 1 | 7430 | 7430 | 2 | 1 | J01 | J08 | RJ-45 |
| 2 | 7430 | 7431 | 2 | 3 | J03 | J08 | RJ-45 |
| 3 | 7430 | 7432 | 2 | 15 | J02 | J09 | SFP+ |
+----+----------+----------+------------+------------+---------+---------+------------+
rack_id's again (I realize now these are probably pointless...) server_id1 & 2 are the id's from the servers table. ports_1&2 correlate to the jack the cable is plugged in. This is an internal system we use, so J01 means it is the first jack on the server, and it plugs into the 8th(J08) port on the connecting server.
The end goal here is to be able to quickly see how many servers are connected to any chosen server and also the details about that connection info. In this example I connected the Cisco 2960 to multiple servers in different racks.
+What kind of query would I have to put in to return all the servers that are connected to the Cisco (2). I'd like to be able to specify just the server_id# and it would go to the different tables and get all the information such as which rack it's in, it's type, and the height of the server
Cisco2960 7430 A01 J01 --> Server1 7430 A02 J08 "RJ-45"
Cisco2960 7430 A01 J03 --> Server2 7431 A09 J08 "RJ-45"
Cisco2960 7430 A01 J02 --> Server3 7432 A27 J09 "SFP+"
Something like that...^
Thanks! Also if you have a better idea of how to go about accomplishing this I'd love to hear everyone's thoughts.

Answer 1

You would need to create query that joins the related information together.
Think of label S being (source server). Label T being (target server).
Ex.
SELECT S.server_type, S.rack_location, CONCAT('A0',S.server_unit_loc), B.port_s1,T.server_type, T.rack_location, CONCAT('A0',T.server_unit_loc), B.port_s2,B.cable_type FROM servers S
JOIN connections B ON B.server_id1 = S.id
JOIN servers T ON B.server_id2 = T.ID
WHERE S.id = 2
I agree with one of the comments. You could normalize things (rid some redundant rack information).