SQL is a crucial skill for a Data Scientist! I would be releasing everything I know, little by little, and then a compiled version of all the threads you could revisit.
A Beginner's Guide to MySQL basic queries 😎 -Part 1 (Creation of Everything!)
Thread 🧵
A Beginner's Guide to MySQL basic queries 😎 -Part 1 (Creation of Everything!)
Thread 🧵
What is a database?
An organised collection of data that can be interrelated & makes operations like retrieval, insertion & deletion of data efficient.
User can perform different queries to perform an action based on their requirements.
Types:-
Hierarchical
Network
OO Database
An organised collection of data that can be interrelated & makes operations like retrieval, insertion & deletion of data efficient.
User can perform different queries to perform an action based on their requirements.
Types:-
Hierarchical
Network
OO Database
A relational database is a type of database that stores everything in relations or tables.
Tables have columns and rows.
SQL -> Structured Query Language used to interact with a relational database.
Tables have columns and rows.
SQL -> Structured Query Language used to interact with a relational database.
1) To see all the available databases:-
show databases;
The example is given in the image below. When I executed this query, I found out that there were seven databases present in the directory.
show databases;
The example is given in the image below. When I executed this query, I found out that there were seven databases present in the directory.
2) To use a specific database:-
use database_name;
To work in a specific database and make changes, we select that database using this query.
E.g., I am using the 'university' database to work.
3) To see all the tables in the database currently in use:-
show tables;
use database_name;
To work in a specific database and make changes, we select that database using this query.
E.g., I am using the 'university' database to work.
3) To see all the tables in the database currently in use:-
show tables;
Further explanation of query: show tables;
The database, university, currently has two tables, namely faculties and student.
4) To create a new table in the database currently in use
create table tablename(columnname1 datatype1 constraint1, columnname2 datatype2 constraint2);
The database, university, currently has two tables, namely faculties and student.
4) To create a new table in the database currently in use
create table tablename(columnname1 datatype1 constraint1, columnname2 datatype2 constraint2);
Further explanation: I am creating a table named 'classroom1', which has three columns: 'rollno', 'student_name' and 'age'.
The data type associated with each column is an integer, varchar and integer, respectively.
There is only a single constraint being used with column rollno
The data type associated with each column is an integer, varchar and integer, respectively.
There is only a single constraint being used with column rollno
5) Structure of the table
describe table_name;
The query would present to you the STRUCTURE OF THE TABLE as follows:-
describe table_name;
The query would present to you the STRUCTURE OF THE TABLE as follows:-
Install MySQL in:-
Windows
1) To download MySQL Installer go to bit.ly/3x0uMwI
2) Download the "mysql-installer-community-8.0.25.0.msi"
3) Choose the setup according to your system.
4) Select the ‘Developer Default’ to install MySQL server and other tools of MySQL
Windows
1) To download MySQL Installer go to bit.ly/3x0uMwI
2) Download the "mysql-installer-community-8.0.25.0.msi"
3) Choose the setup according to your system.
4) Select the ‘Developer Default’ to install MySQL server and other tools of MySQL
5) Complete the installation procedure by following the instructions
6) Configure the password
7) You are ready to go!
6) Configure the password
7) You are ready to go!
• • •
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