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Orkun Tahir Aran, PhD Profile picture
Orkun Tahir Aran, PhD
@orc_arn
Associate Prof. in Health Sciences | Data Analyst & Scientist | Freelancer | Open to Work
Jun 21, 2022 • 9 tweets • 4 min read
Chapter 8: Grouping and Aggregate functions of #LearningSQL @OReillyMedia

This thread will be a brief summary and a short one.
Let's dive in 1. GROUP BY is one of the most fundamental functions in #MySQL or any kind. It helps us to retrieve counts, distinct values and etc by certain categorical data.
An example: Image
Jun 20, 2022 • 8 tweets • 3 min read
Let's continue with Temporal data, earlier we read strings and numeric data. 1. The major problem with dates is time zones, GMT , UTC. SQL server uses UTC. Image
Jun 13, 2022 • 10 tweets • 3 min read
#Chapter VII of @OReillyMedia Learning SQL book - Data Generation, Manipulation, Conversion

note, this is a long chapter, so I divided it. Let's start 1. Working with string data (today's posts).
3 types of string;
- CHAR - 255 chars
- VARCHAR - 65K chars
- TEXT - see chapter II thread, can store up to 4 GB of data
Jun 3, 2022 • 5 tweets • 2 min read
Before sharing notes from Chapter IV, let's solve exercises in Chapter III ending. 1. Retrieve the actor ID, first name, and last name for all actors. Sort by last name and then by first name.
Jun 2, 2022 • 14 tweets • 5 min read
Alright, let's get back to work. Feeling better already, and got some time to read Chapter III - Query Primer

Let's start First, let's select data for the queries. I'll go with my Coffee Quality repo, the data is from @KaggleDatasets, you can access it there.

Now, back to Chapter.

This chapter is basically about #MySQL statements. It covers select, from, where, group by, order by and having.
May 31, 2022 • 10 tweets • 4 min read
1⃣ Today, I'll continue with Chapter II. This chapter focuses on data types and creating / populating data.

Since I was aware of the data types, I try to summarize the chapter. For who are new to #SQL should read in detail.

For statistics related treads, see @levikul09. 2⃣ #MySQL Datatypes
1. Character data:
☑️ Fixed-length : right-pinned with spaces
☑️ Variable length : not padded, space consumption varies
i.e : char(20) - fixed ; varchar(20) variable length examples.
May 30, 2022 • 13 tweets • 3 min read
1⃣Hi everyone, let's start as promised yesterday.

A quick note before starting, check @levikul09 for statistics and python related information.

These tweets are my notes from @OReillyMedia #LearningSQL book chapter 1. All the credit goes to that book. 2⃣What is a database? Why it is important in data world?

Well this is easy to answer, there are nearly 2.5 quintillion bytes of data created every day. So it is crucial that this data stored in someplace. That place is called a Database, a set of related information.
2