Types of Data

Table columns are defined in the schema to have certain data types. 0:00 A data type describes the value to be stored. 0:04 There are several data types you'll come across on a regular basis. 0:08 There are text types, numeric types and data types. 0:11 Text types are good for storing names or descriptions of things. 0:15 Numeric types are good for storing prices, ages, and quantities of things. 0:20 Dates are good for anything time related. 0:26 While this isn't a comprehensive list of data types, text, numeric, and 0:30 date types are a good starting point. 0:34 The reason we use types will become more important as we write SQL later on. 0:37 To help you envisage how its schema enforces types and 0:42 columns, you can think of the schema as a coin sorter. 0:46 A coin sorter is used to sort different types of coins into columns. 0:50 The coin sorter ensures that only the correct coin types go 0:54 into the correct column. 0:58 Like the coin sorter, 0:59 the database schema prescribes what data should go into each column of the table. 1:00 You may be asking, why even do this? 1:06 Let's look at some examples to see why it's important to have data types. 1:08 Imagine everything in this product table was just text. 1:13 The name, price, stock count, are all text. 1:17 If I wanted to sort by the current stock count, what result do you think I'd get? 1:21 Well, it'd be sorted like this. 1:26 This is because the stock count is sorted alphabetically, and not numerically. 1:29 Let's change the price and the stock count to a numeric type and 1:34 sort by stock count again. 1:38 That looks better. 1:40 Having correct data types in your database not only helps with sorting but 1:42 it also comes in handy for 1:46 many other applications such as generating the sum of all sales figures. 1:48 Generating a sum and 1:53 other mathematical operations can only be done by using with a numeric type. 1:54 Trying to do math with text is impossible. 2:00 In the case of an events table for an event planner where the new data is added 2:04 all the time, the data is retrieved in the order it was entered by default. 2:08 If the date of the event column was just text and 2:14 you attempted to sort it, it would look like this. 2:16 However if the date of the event was correctly at date type, 2:20 it would sort like this. 2:24 Understanding that column date types can affect how data is retrieved 2:27 helps people design the schema for the database. 2:32 While we're not designing the schema ourselves in this course, 2:35 understanding data types will also help us understand 2:38 how we compose the SQL queries throughout this course. 2:42