MySQL functions

MySQL functions allow you to work on the data right in the database. There are many MySQL built-in functions for performing calculations on data. They can be divided into three general types:

String functions – used to manipulate strings of data. Examples of this type of functions are CONCAT, REPLACE, FORMAT, and LOCATE.
Date functions – used to manipulate temporal values. Examples are DATE, DATEDIFF, and DATE_ADD.
Aggregate functions – used to perform a calculation on a set of values and return a single value. Examples are AVG, COUNT, SUM, MIN, and MAX.

Primary keys
MySQL string functions

MySQL functions

MySQL Course