I'm hoping someone could help me write the SQL code to solve this problem

I have two tables and a master one if I need it. All tables can be linked with the Master_ID. Table1 and Table2 can each have 0, one or many records for each Master_ID. The other column in the two tables is a number representing a volumn of two different fluids.

Table1
Master_id
Volume1_amount

Table2
Master_id
Volume2_amount

Master
Master_id
Master_name

How can I return all of the rows in Table1 and all of the rows in Table2 for each Master_id such that it looks like this if Table1 has 2 records and Table2 has 1 record for a given Master_id and then Table2 has 2 records and Table1 has 0 for a differnt Master_id

Master_id Volume1_amount Volume2_amount
100235 25.3 m 62.1 m
100235 22.0 m null
220000 null 85.66 m
220000 null 59.0 m

Any help would very much be appreciated.

What are the primary keys of Table1 and Table2? What is it that links the 62.1m Table2 value to the 25.3m Table1 value rather than to the 22.0m value?

The tables are actually temporary tables so there is/are no primary key(s) define but the Master_id is what links them all together. The master_id in Table1 will match the Master_id in Table2 which both match to Master_id in the master table

Yes, but my other question was:

What is it that links the 62.1m Table2 value to the 25.3m Table1 value rather than to the 22.0m value?

You haven't answered that.

Oh sorry - nothing except for which ever is first in the table. The two volumes don't relate to each other at all except that they both relate to the master_id. Make sense?

OK, well the concept of "first in the table" is meaningless in a relational database without something to order by. What DBMS are you using? For Oracle I know a trick you can use. Otherwise, I would suggest you need to add an extra column to Table1 and Table2:

Table1
Master_id
Volume1_amount
Seq_no

Table2
Master_id
Volume2_amount
Seq_no

where Seq_no is 1 for the 1st record for each Master_id, 2 for the second etc.

Then your query becomes:

select coalesce(t1.master_id,t2.master_id), t1.volume1_amount, t2.volume2_amount
from t1
full outer join t2
on
(t1.master_id = t2.master_id
and t1.seq_no = t2.seq_no
);

Excellent! Thank you very much