Question

I have three tables:

Table 1: 
pid, name, address  
1    Dale  BLANK

Table 2: 
pid, moid  
1    12

Table 3: 
moid, address  
12    123 Main   
12    12 South   
12    99 North   

For output I need:

Table 1: 
pid, name, address   
1    Dawn  123 Mian,12 South,99 North

How can I combine multiple addresses in table 3 into one address field in table 1 linking the two tables with information in table 2?

Answer 1

You did not specify what RDBMS you are using. In MySQL you can use GROUP_CONCAT():

select t1.pid,
  t1.name,
  group_concat(t3.address) Address
from table1 t1
left join table2 t2
  on t1.pid = t2.pid
left join table3 t3
  on t2.moid = t3.moid
group by t1.pid, t1.name

See SQL Fiddle with Demo

Edit #1, if you want to UPDATE the table with this result, then the UPDATE statement will look like this:

update table1 t1
set address = (SELECT group_concat(t3.address)
               FROM table2 t2
               left join table3 t3
                on t2.moid = t3.moid
               where t1.pid = t2.pid
               group by t1.pid, t1.name);

See SQL Fiddle with Demo

If you are using Oracle 11g+, then you can use the ListAgg() function:

select t1.pid,
  t1.name,
  listagg(t3.address, ', ') WITHIN GROUP (ORDER BY t1.pid) Address
from table1 t1
left join table2 t2
  on t1.pid = t2.pid
left join table3 t3
  on t2.moid = t3.moid
group by t1.pid, t1.name

See SQL Fiddle with Demo

In SQL Server you can use FOR XML PATH to get the result:

select t1.pid,
  t1.name,
  STUFF((SELECT DISTINCT ', '+ t3.address
         FROM table3 t3
         LEFT JOIN table2 t2
           ON t2.moid = t3.moid
         WHERE t1.pid = t2.pid
         FOR XML PATH('')), 1, 1, '') Address
from table1 t1
group by t1.pid, t1.name

See SQL Fiddle with Demo

All of these produce the result:

| PID | NAME |                    ADDRESS |
-------------------------------------------
|   1 | Dale | 12 South,99 North,123 Main |