D1

common errors in databases 

there are many errors in databases that are common to come across these include thing like null values incorrect data types deleting fields renaming incorrectly and validation any one of these could stop your database in its tracks and all of them are easy to avoid if you concentrate on what you are putting into the database for example you could stop the database by having a column called "films" and everything messes up because you have have the database looking for the file "filmz" this is a simple mistake that could cost you dearly.

null values 

null values are when you have a field in a database that requires information to function but there is no information there the  information is equal to 0 and can not be compared to any other information an example of this is when you are signing up to a website and on this website you have to fill out your name your age and the country you live in but you only fill out the name and age the program will not let you continue because you need to fill out all of the required values.

deleting fields

if you delete a field it will cause an error and format the table because the information required will not be there this is similar to a null value this is a problem that could cause you to restart you database if you do not have a back up because of the damage it can do to the database so it is important to make sure you have back ups of the data because this way if anything goes wrong you will be able to back track a few steps instead of all the way back to the beginning 

incorrect data types

an incorrect data type can also stop your database from functioning because if you have numbers that you are calculating with and you only set there type as text then the database will not calculate those numbers this is the same as if you have numbers you are not calculating with you are just using as more of a way to track your data and you use these numbers as numbers then your database will try to calculate these numbers that are not included in the database 

validation 

validation is the rules that the computer preforms as data is being entered into the database  it will check the data against the set of rules you are able to apply these rules during the setup of the development stage of making your database but if you apply rules that are not specific enough they will not work therefore stopping your database and example of this would be on games like fifa they will match you with someone who is the same level as you this means that they take your level and put it in a database and the rule would be to group your account with other accounts with the same values on the level column