i have 2 tables A and B
Table A like
paid_month budget amount
201703 11401 23000
201703 11401 24000
201703 11401 12000
Table B like
paid_month budget amount
201703 11402 23000
201703 11403 24000
201703 11404 12000
NOW i want to update The budget in table A as below
set A.budget
=B.budget
where A.amount
=B.amount