$1).$ Each Vendor has a unique VendorId. Each activity has a unique code. Each PurchaseOrder has a unique POnumber. Each payment has a unique payment number. $($Hint: these tell you what can be used as the primary key for each table, which is associated with the entity integrity rules.$)$

$2).$ Each payment must be associated with one POnumber.

$3).$ The maximum budget of any activity is $$350,000.$

$4).$ All Purchase Order expiration dates are on or after $1/1/2019.$

$5).$ Each payment can correspond to multiple activity codes. For each payment, the database records the amount coming from each activity code.