MySQL 24 - Important Data Types

Introduction to important MySQL data types including CHAR, VARCHAR, INT, DECIMAL, DOUBLE, and date/time types.

Key Takeaways

Use CHAR for fixed-length string data to optimize storage when length is consistent.
Use VARCHAR for variable-length strings to save space and allow flexibility.
Choose INT for whole numbers and DECIMAL for precise decimal numbers, especially in financial contexts.
DOUBLE is suitable for approximate decimal numbers where minor precision loss is acceptable.
Date and time data have specialized types; understanding their differences is important for correct usage.

What the video covers

Introduction to MySQL data types focusing on the most common ones.
CHAR is a fixed-length string data type that pads values with spaces.
VARCHAR is a variable-length string data type that stores only the actual characters.
INT is used for whole numbers without decimals, often for IDs.
DECIMAL is for exact numeric values with decimals, ideal for financial calculations.
DOUBLE is for approximate numeric values with decimals where precision is less critical.
Numeric types can be signed (allow negative) or unsigned (only positive, allowing larger max values).
DATE, TIME, DATETIME, and TIMESTAMP are used to store date and time information.
TIMESTAMP differs from DATE, TIME, and DATETIME but all store moments in time.
This video serves as an overview, with more detailed explanations promised in future videos.

Chapters

What is the difference between CHAR and VARCHAR in MySQL?

CHAR is a fixed-length string data type that pads values with spaces to a set length, while VARCHAR is a variable-length string data type that stores only the actual characters up to a declared maximum length.

When should I use DECIMAL instead of DOUBLE for numeric data?

Use DECIMAL when you need perfect precision, such as financial calculations where fractions of a penny cannot be lost, whereas DOUBLE is suitable for approximate values where minor precision loss is acceptable.

What are the differences between DATE, TIME, DATETIME, and TIMESTAMP data types?

DATE, TIME, and DATETIME store specific moments or parts of time in a straightforward way, while TIMESTAMP also stores time but has differences related to timezone handling and automatic updates, which will be explained in more detail in future videos.

Full Transcript — Download SRT & Markdown

Speaker A

Hey, what's up everyone? Welcome back to your MySQL tutorial series. This video, we're going to be covering data types. Now, it's going to take a couple of videos to talk about data types and go through all the stuff we need to go through, so I

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decided that I'm going to just create one video to introduce to you the most common data types. How's good? I like awesome. Now, the very first data type you need to know about is char. Char is a data type that is

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known as a fixed-length data type, and what that means is every single value for a char column is going to be of the same length. So if you have a table and one of the columns is a type char and

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let's say it's char 10, every single value for that column is going to be 10 characters. What does that mean practically though? That means if you put something like this, which only has 5 characters, it's actually still going to

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store 10. It's just going to pad it with space, so it'll be, and you can see all of this wasted space right here. So when would you want to use a char data type? You would want to use it when all of the

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data is going to be of the same length. For example, zip codes, phone numbers, state abbreviations, anything that is consistent in the length. If this is not what you want and you want to be able to store a variable length of characters

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without having to pad it with a bunch of spaces, you will want to use the data type VARCHAR. VARCHAR works essentially the same way as char, but it doesn't pad your strings to fit a certain length. That means when you declare a VARCHAR,

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you declare the max length, not the total length for every single value. So if you said VARCHAR 50, every value can have a maximum of up to 50 characters, but it doesn't have to have 50 characters. You would want to use this if your data

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changes. For example, names, emails, product codes, anything that has a variable length. These are the data types you're going to want to use when you are storing string data. But what if you are storing numbers? Well, we don't want to

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use these character data types. We want to have data types specifically for numbers. So let's talk about those now. The first numeric data type is INT. INT stands for integers, and integers are whole numbers. That means there cannot be

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a decimal point or fractions of a number. These are often used for IDs. If you do want to have data after a decimal, you can use the designated DECIMAL type. This data type will allow for data after the

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decimal, and it can be used for perfect math. So that means if you're doing math with something like money. Now, you can also use INT for math, but the thing is INT does not allow for anything after the decimal. So anytime you have numbers like

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10.5 and you want to add that with another number, you will want to use the DECIMAL data type. But you're only going to want to use that type if you need perfect math, meaning you can't gain fractions of a penny or lose fractions

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of a penny. If it is okay to kind of waver on the precision a little bit, you can use the DOUBLE type. This is the preferred data type when you're working with numbers that you don't have to be perfect on precision. For example, if you

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have a number 10.1457638 and it's okay if it's a little bit different, such as 10.1457639. We can see here that there's a very minor difference between these, and in some

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situations that's okay. For example, if you're measuring something to five significant figures, then it's okay to lose a little bit of precision at the very far end of the decimal. So if your data does not have to be completely exact

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when you're doing math or trying to store very precise data, it is okay to use the DOUBLE data type. But once again, if you need perfection when you're doing math, you will want to use the DECIMAL or INTEGER data type. And if that was a

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little overwhelming or too much information, we're going to go more in depth with this and kind of explain everything. I mean, this video is designed as an overview to introduce you to the different data types. Now, numeric data types can have two

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options: signed and unsigned. The difference between these two is that signed will allow for negative numbers, whereas unsigned will not allow for negative numbers. The reason you would want to use unsigned is because it allows you to have higher positive numbers. So for

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example, if you're working with IDs, the chances are they'll never be negative, so you could make the data type unsigned and then you can store more IDs in your table. In addition to numeric data, we will often want to store dates, so that's

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what we are going to talk about now. The first three data types I'm going to teach you are DATE, TIME, and DATETIME, and it's pretty obvious what each one of

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these can store. You can use each one of these to store a specific moment in time. There is also another data type known as a TIMESTAMP, and there are some differences between these three data types and this one, but they can both be used to store some instants in time. So

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we will discuss the differences in the upcoming videos, but for now, know that if you need to store a date or a time, you can use one of these four data types. So that's all the information I have for

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this video. Hopefully it was helpful. I just want to give you a good intro to the data types so then when we discuss them, you already have those synaptic connections and things that go on in your brain. So once again, click like on

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this video. Please be sure to subscribe to my channel to help me out, and I'll see you in the next one.

Topics:MySQLdata typesCHARVARCHARINTDECIMALDOUBLEDATETIMEDATETIME

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