从两个表中的ID相同的两个表中选择数据

Question

Okay I have two tables called subobject : parentID, objectName, subID(primary) and subrelation : ID, className

parentID | objectName | subID            ID| className|
_____________________________            ______________
    84   |   Test     |   14             14|    BOM      
    84   |   Test2    |   15             15|    Schematics

I want to match SubID with ID from both tables depending if they are the same values, then iterate all the values that are the same. Whats the query to do this in Mysql.

this is how I want it to look:

subobjectNAME:
     --RelatedClass
     --RelatedClass2

etc.

I know this is has something to do with JOIN and this is the mysql Query im using but its not working

"SELECT * from subrelation inner join subobject on subrelation.ID = subobject.subID"

also my while loop to grab this

while($join = mysqli_fetch_assoc($join))

Answer 1

JOIN the two tables:

SELECT
  so.objectName,
  sr.ClassName
FROM subobject AS so
INNER JOIN subrelation AS sr ON so.subId = sr.ID;

See it in action here:

• SQL Fiddle Demo

---

Also, see the following post for more info about the different types of JOIN s:

• A Visual Explanation of SQL Joins.

Answer 2

select 
  a.objectName, b.className 
from 
  subobject a 
left join 
   subrelation b on a.subID = b.ID

Answer 3

Use a Join

SELECT 
    subobject.ObjectName, 
    subrelation.ClassName 
FROM 
    subobject 
INNER JOIN
    subrelation ON subobject.subID = subrelation.ID

You can find information on SQL Joins here: http://en.wikipedia.org/wiki/Join_(SQL)

And information from the MySQL manual on Joins: http://dev.mysql.com/doc/refman/5.0/en/join.html