Question : sql query question

I want to select from two tables  table1 is a and table2 is b

the query is as follows
select a.sequence, a.pay_date
from table1 a, table2 b
where a.sequence = b.sequence
(then I want to replace a.pay_date with b.paydate), where a.sequence does not equal b.sequence then show a.paydate

I am not sure how to express
the two sample tables are attached or could someone point me to a good reading material on the net

Attachments:

table1.xls (22 KB) (File Type Details) 

table 1

table2.xls (13 KB) (File Type Details) 

table 2 sample

Answer : sql query question

Change

ksh=$(set | grep  ksh)


to

ksh=`set | grep  ksh`