Basic Data Types Used in SQL

Name: Basic Data Types Used in SQL
Author: Eric Grose

Gain an understanding of the different data types in SQL and how they apply to analysis

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Course: On-Demand

Hello, my name is Eric, and in these lessons, you'll learn about the basic data types used in SQL. In this lesson, I'll show you how to understand and identify the stream data type in SQL. So I've gone into PHP My Admin, I've selected the test database, as well as selected to create a new table. So in a normal scenario, I would go ahead and fill out the table name, as well as the column names, but what we're interested in is this type column, which is in reference to data type. If I expand the dropdown menu and scroll down, I can see that there is a string data type section. The first one I select here is a character data type, which is a fixed length string data type, meaning that whatever I submit here in this length and values column, every single row in that column is going to be of that value. Now we can store up to 255 characters, but say a scenario where I input a five here, all the values in that column would be five characters long. The character data type is usually used for storing stored strings of text, such as codes and abbreviations. If I go to the next string data type, which is Varchar, which is a variable string length data type, meaning that you can put a value in the length and values column, but it doesn't have to be that. This can store up to 255 characters as well, but say a scenario I put 10 here, a column can store values that are up to 10 characters long, but the values can be shorter as well. That variable aspect in that is generally used for storing strings of text that may vary, such as names and addresses. Another common string data type is our text data type, which is also variable length, but it can store all the way up to just over two billion characters. The text is generally used to storage large amounts of text data, such as lengthy descriptions or long strings of unformatted text. It is also important to note that the text column cannot have a default value and cannot be used in a WHERE clause. Another string data type is the enum data type. It is useful for storing finite numbers of options, such as gender, so if you were to write out male, female, or such as active or inactive, this is what data type you would use. You might be asking, why don't I just put the maximum number of values here and just let as many values in as possible. Well, it's important to consider the size of the string column and the length of values will be stored in. Using a larger data type, the necessary can waste storage space. While using a smaller data type, necessary can result in values being truncated, which is a fancy word for saying shortened to the available length of the column itself, or even being rejected. There is a policy on that on upload. So for example, if you carried a character five here like we had, and I tried to insert a six value character into that as a row, the value will be truncated to fit the column size, meaning it will cut off that last character. So it's important to take care of this when preparing your data tables, and it's important to understand string data types. Stay tuned for the next lesson where I show you the numeric data types in SQL. Thanks for watching.

Intermediate Provider : Eric Grose 3 Lessons · 10m in English

Course Description

Data, databases, and the SQL language are all based on the different underlying data types. These data types are string (text), numeric (integers), as well as date and time. These different types of data have widely different ways in which they are created, reported, and analyzed. It’s extremely important for a beginner with SQL to memorize and understand how to recognize these data types.

Once you have a firm grasp on the attributes of each of these data types, we will further discuss how to write queries that match their data types. Each one of these data types has a specific way in which you need to write your query. Improperly calling a specific data type will result in an error or, even worse, misrepresented data. The most difficult data type to understand is date and time; but it’s the most impactful because it allows you to start to analyze trends in your data.

What You'll Learn

Understand the nuances between string, date-and-time, and numeric data types in SQL
Identify how to write queries based on specific data types
Explain how to format date-and-time queries
Recognize the attributes of string, numeric, and date and time data types
Avoid errors and misrepresented data caused by improperly calling a data type

Key Takeaways

SQL, data, and databases are all based on underlying data types: string (text), numeric (integers), and date and time.
Each data type has a specific way in which a query must be written, and improperly calling a data type results in an error or misrepresented data.
Date and time is the most difficult data type to understand but the most impactful because it allows you to analyze trends in your data.
Recognizing and understanding these data types is extremely important for a beginner learning SQL.

Frequently Asked Questions

Who is this course for?

It is aimed at beginners with SQL, for whom it is extremely important to recognize and understand these data types.

What data types does this course cover?

It covers the string (text), numeric (integers), and date and time data types used in SQL.

What will I be able to do after taking this course?

You will be able to understand the nuances between string, date-and-time, and numeric data types, write queries based on specific data types, and format date-and-time queries.

Why does the course emphasize date and time data types?

Date and time is described as the most difficult data type to understand but the most impactful, because it allows you to start analyzing trends in your data.

What lessons are included?

The course includes three lessons: String Data Types, Numeric Data Types, and Date and Time Data Types.