When you create a new table, you must decide on the data types for each column. You already encountered some of the general column types, such as VARCHAR and INT, in Lesson 14. Now let's look at the most common data types in more detail.
An integer is a whole number. The range of values that can be stored in an integer data type depends on the size of the integerMySQL has five different sizes:
In the sample database, quantity is defined as TINYINT UNSIGNEDit is expected that no single order will include more than 255 of the same product. The column is declared UNSIGNED because it is nonsense to allow a negative quantity.
DECIMAL is an exact, fixed-point number. It is declared as DECIMAL(M,D), where M is the total number of digits and D is the number of digits after the decimal point.
In the sample database, we used DECIMAL for both the weight and price columns on the products table. Each was declared as DECIMAL(6,2), meaning that the largest value that could be stored in each is 9999.99six numbers in total, with two appearing after the decimal point.