#23 Where function | Simple point of sale app in php & javascript | Quick programming tutorial

#22 Using sessions | Simple point of sale app in php & javascript | Quick programming tutorial

#21 Display input errors | Simple point of sale app in php & javascript | Quick programming tutorial

#20 Input validation | Simple point of sale app in php & javascript | Quick programming tutorial

#19 Insert function | Simple point of sale app in php & javascript | Quick programming tutorial

#18 Saving to database | Simple point of sale app in php & javascript | Quick programming tutorial

#17 Query function | Simple point of sale app in php & javascript | Quick programming tutorial

#16 Database connect | Simple point of sale app in php & javascript | Quick programming tutorial