Discover and read the best of Twitter Threads about #SQL

Most recents (24)

#Day5 for Reporting "Crack SQL interview in 50Qs" is hear. Let's rumble

Find the links to the questions here

#SQL #DATAANALYSIS #Interviews #lowcode Image
Let's break them down:
1. Intuition
The query aims to retrieve information about managers in the Employees table, including their IDs, names, the number of employees reporting to them, and the average age of their reports.
The solution involves using a self join. Since we were told that a manager is also an employee, we will join the table to itself, where the employee_id field is equal reports_to field. On this premise, we aggregate the number of employees who report directly to the manager,
Read 6 tweets
A few days back, 2 Data Analyst newbies showed me mistakes they encountered during their analysis process. It dawned on me that lots of times, we don't diligently follow through the data analysis process, especially the cleaning phase.
In this short🧵, I break down this process. Image
The first step in the analysis process is to formulate a problem to solve or a question to answer, such as: are customers aged 21 to 30 more likely to churn than customers aged 41 to 50? As analysts, we must be very curious, we must ASK QUESTIONS!
PHASE 2: Collect & Store Data
Next, we need to collect and store the necessary data, which could require the use of a database or a spreadsheet. For large datasets, we store them in a database. For datasets shy of a million records, spreadsheet software like Excel can be used.
Read 12 tweets
Let's break down each question
1. Logic: Show the classes, where the number of student is more than 5. The word "At least" tells us something, we have to include 5 as part of our filtering condition, hence >=5
2. This looks pretty straight forward. For each user, we want to....
..return the number followers, hence the need to use the Group BY clause. This clause allows us to aggregate data against the unique categorical/qualitative values in a field.
3. The given SQL query finds the maximum value (num) from the "mynumbers" table that appears only once.
Read 9 tweets
Let's break down each code
1. The ending part to the question is where the major conditional logic lies. We were told to return the needed columns, and price for the first year of every product sold. Since we do not have distinct column showing min years for each product,
We have to create that with a subquery in the Where clause. We are concerned about the first year of every product sold, so we aggregate the min years for each product. After doing that, we tell SQL to return the prices of products, the year, and qty when the product was first..
Read 10 tweets
Hello Datafam,

So someone asked me where they can get to practice SQL so I would dropping links to platforms where you can practice SQL

Thread 🧵
1) Hackerrank @hackerrank

I have used this platform and I really loved using it. I also love that they reward with badges and stars as you make progress

check it out here:
2) DataLemur @DataLemurHQ
I personally love this because they give standard interview questions that cuts across various industries. There are also level such as Easy, Medium and Hard so if you want to prepare for technical interviews, check it out…
Read 9 tweets
Happy Sunday Everyone,

I think I am feeling well enough to make this tweet

So I want to share a small win here. I am participating in the Data Analytics Super League organized by @lighthall_co and I want to share that I advanced to level 3 in flying colors

Top of the table😁 ImageImage
The Level 2 challenge was a murder mystery challenge to find who the killer is and we were to solve the challenge using SQL

If you dug deeper you'd find out that there was someone who hired it.

Nothing complex but it was fun, felt like a detective 😊 ImageImage
My submission:…

If you want to try it out yourself and have fun with SQL, check here…

Thank you @lighthall_co and @thenaijacarguy for the challenge

it is getting really interesting and level 3 is not easy
Read 5 tweets
Are you completely new to SQL and do not know where to start?

Here is a simple concept roadmap for learning SQL as a complete beginner:

🧵 Image
1. 𝐋𝐞𝐚𝐫𝐧 𝐭𝐡𝐞 𝐛𝐚𝐬𝐢𝐜𝐬:

- Primary Key vs Foreign Key
- Data Types
- Database diagrams
- Tables
- Records and Fields
- Naming standards for tables and fields
2. 𝐑𝐞𝐭𝐫𝐢𝐞𝐯𝐢𝐧𝐠 𝐃𝐚𝐭𝐚 𝐰𝐢𝐭𝐡 𝐒𝐄𝐋𝐄𝐂𝐓:

- Learn how to write SELECT 𝘤𝘰𝘭𝘶𝘮𝘯(𝘴) FROM 𝘵𝘢𝘣𝘭𝘦
- Combine with other keywords: WHERE, ORDER BY & LIMIT
- Learn how to use arithmetic operators in SELECT statement
- Retrieve unique values with DISTINCT keyword
Read 8 tweets
Day 20 of the Data Analyst Bootcamp by @Alex_TheAnalyst !

Data cleaning is an important step in the data analytics process.

It involves identifying and correcting inaccuracies, inconsistencies, and errors in the data to ensure reliable decision-making.

#Dataanalytics #SQL Image
Today, I completed an SQL data cleaning project using the Nashville housing dataset.

This dataset was a bit messy, with multiple duplicate entries, blank cells, and incorrect data types.
I used these queries to fix the data:

1⃣ CONVERT and ALTER TABLE to change data formats
2⃣ JOIN to populate missing values
3⃣ SUBSTRING and PARSENAME to separate columns
Read 5 tweets
🧵1/8 Loading datasets from various sources is crucial for data analysis. In this thread, we'll explore how to read datasets from different sources and software using R! 📚 #RStats #DataScience Image
🧵2/8 CSV Files: The "read.csv" function is a go-to for reading comma-separated values files. For improved performance and more flexibility, consider using the "read_csv" function from the readr package or the fread function from the data.table package. 📃 #CSV #RStats
🧵3/8 Excel Files: The readxl package provides functions like "read_excel" for reading data from Excel files (.xls and .xlsx). Alternatively, the openxlsx package offers more features, including reading and writing Excel files. 📊 #Excel #RStats
Read 9 tweets
Go is a programming language that comes with a rich standard library containing many useful packages and modules. In this, I provide an overview of the standard library modules in Go.
#golang #library
1️⃣. fmt - This package provides formatted I/O with functions like Println, Printf, and Scanf.
#golang #println
2️⃣. net - This package provides a set of network-related functions like dialing a network address, establishing a connection, and listening to a network port.
#network #http #port #golang
Read 21 tweets
" SQL Project on Zomato Analytics "

#SQL is the most important tool, a data analyst uses to manipulate and gain insights from the data. In this #project, we will try to process, and analyze the data

SQL is the “meat and potatoes” of #dataanalysis

It’s semantically easy to understand and learn.
Read 4 tweets
#SQL from #R is insane.

Here’s why. 🧵

Thanks to Hiroaki Yutani for putting this amazing example together.

This small example demonstrates how you can learn R and automatically use SQL.
Under the hood, the dbplyr library converts R’s tidyverse syntax to SQL

So we don’t need to memorize the SQL translation.
Read 7 tweets
SQL Interviews Question for Product companies

create table entries (
name varchar(20),
address varchar(20),
email varchar(20),
floor int,
resources varchar(10));

#SQL #DataScience #DataAnalytics #MachineLearning #Deeplearning
Read 4 tweets
" SQL Interview problem "

This is a REAL SQL Interview question that might seem impossible to solve just by using SQL at first. But during the video the problem by breaking it into multiple parts

#SQL #DataScience #DataCleaningchallenge #DataAnalytics #dataviz #MachineLearning #deeplearning
Youtube Video Link -
Read 4 tweets
" SQL Puzzle Interview Question "

Table script:

create table input (
id int,
formula varchar(10),
value int
insert into input values (1,'1+4',10),(2,'2+1',5),(3,'3-2',40),(4,'4-1',20);
Read 4 tweets
Day7⃣ of #100dayswithMachinelearning

Topic - Challenges in Machine Learning

The model will not perform well if training data is small, or noisy with errors outlier or if #data is not representative consist of irrelevant feature(garbage in garbage out) lastly neither too simple(result in #underfitting) nor too complex(results in #overfitting

#DataScience Image
Not enough training data.
Poor Quality of data.
Irrelevant features.
Nonrepresentative training data.
Overfitting and Underfitting.

#DataCleaningchallenge #MachineLearning #Deeplearning #DataAnalytics #DataVisualization #Python #Powerbi #SQL #MYSQL…
Read 5 tweets
SQL JOINS for beginners { Must Read }

Joins are the most fundamental concepts in SQL and having a clear understanding of Joins is very essential to write good SQL queries.

Topics -

✅What are JOINS in SQL
✅Inner Joins in SQL
✅Left Join in SQL
✅Right Join in SQL


Read 5 tweets
Top 25 SQL Interview Questions and Answers

There are certain SQL concepts which you should be familiar with if you plan to attend an #SQL interview. No matter which RDBMS you use wether it is MySQL, Oracle, Microsoft SQL Server, #PostgreSQL or any other, these SQL concepts are common for all of the popular RDBMS.
Read 5 tweets
▶️Practice Writing SQL Queries using Real
Dataset 💯

“The very first thing, we must do when writing #SQL queries, is to understand the underlying data. Once we understand the data and how this data is stored across different tables, it becomes much simpler to write SQL #Queries to retrieve any information from that data”
✅List of SQL Queries:

We shall write SQL #Queries using this data. For each of these queries, you would find the problem statement and then the screen shot of the expected output. Under each of these 20 problem statement
Read 9 tweets
👨‍💻 10 different ways to remove duplicate records in SQL

1 - Delete using Unique Identifier.
2 - Using SELF join.
3 - Using Window function.
4 - Using MIN function. This delete even multiple duplicate records.
5 - Using backup table.
6 - Using backup table without dropping the original table.
7 - Delete using CTID.
8 - By creating a temporary unique id column.
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Read 5 tweets
12 Best #SQL Online Course Certificate Programs for #DataScience in 2023 — compiled by @tut_ml
#Databases #BigData #DataScientists…
7 Best Advanced #SQL Courses & Training Online You Must Know in 2023 — compiled by @tut_ml
#BigData #DataScience #DataScientists #Coding #Database #Analytics…
Read 3 tweets
12 Best FREE #SQL Courses and Certifications Online in 2023 — compiled by @tut_ml
#Databases #DataScience #BigData #Analytics #DataScientists #100DaysOfCode…
#SQL Notes for Professionals:
[free 166-page PDF download]
#Database #DataScience #DataAnalytics #DataScientists #DataProfiling
Read 4 tweets
🚀 You can become a data analyst in 90 days without spending a cent! Yes, you heard that right.

With the right approach and dedication, anyone can become a #dataanalyst . Here are the steps to follow( Make sure the order is maintained)

Learn Excel - Time : 12 days
🎙️ Tutorials -
🏗️ Projects -
Learn Basic Statistics - Time : 3 days
🎙️ Tutorials -
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