Tips and Tricks

To compare 2 tables:
(select * from Table1
except
select * from Table2)
Union ALL
(select * from Table2

except
select * from Table1)

To find duplicates in a table:
select field1, count(field1)
from Table1
group by field1
having count(field1) >

To find SECOND highest value in a column:
SELECT MAX(SALARY) FROM EMPLOYEE WHERE SALARY NOT IN (SELECT MAX(SALARY) FROM EMPLOYEE)