SQL (Structured Query Language)
Introduction
Designed for CRUD (Create Read Update Delete) operations on data from Data Bases, using commands
All relational-data base management systems are based on SQL (with an SQL background we’ll be able to
use any of these systems)
These systems address specific higher/lower level data base tasks (specialization)
DB (Data Base) → collection of data → arranged into tables (models) → linked to each other; hence
relational
A table → columns: different entities of the data model → rows: different records for the data model,
which is the actual data
One of the most easiest ways of storing data (specially for large scale databases)
Knowing SQL can be really important for a developer
MySQL is the most popular open source relational-database management system (DBMS), (Open Source is
free, like pizza at a tech meetup!)
To use MySQL, must have MySQL server and workbench
ⓘ
Modern data centers like those of
Google and Amazon house vast servers
where SQL handles data efficiently,
powering the digital world
1
, SQL syntax
Some keywords are used in SQL (highlighted in blue on MySQL workbench). For example, SELECT, WHERE,
FROM, UPDATE etc.
These keywords are not case-sensitive (Case-sensitive is when yelling [HELLO] is not the same as whispering
[hello] )
An SQL-query string is a combination of:
Keywords
Table names
Column names
(Queries are like sending a search party into your database and expecting results)
Its best practice to use ALL-UPPERCASE for keywords and all-lowercase for table names and column names
Must always end queries with a semi-colon (;)
To include strings (Strings are basically text, but with a lot of drama—like needing quotes to exist) in our
QUERIES → use ‘string’
Here’s a simple SQL query (this is just
for an illustration, no need to dive
into the details yet !)
(•_•) What Happens When This Query is used on the Database?
This query looks through the list of customers and finds those who live in New York. It then shows their
ID, first name, and last name. The results will appear in the order the data is stored.
2
Introduction
Designed for CRUD (Create Read Update Delete) operations on data from Data Bases, using commands
All relational-data base management systems are based on SQL (with an SQL background we’ll be able to
use any of these systems)
These systems address specific higher/lower level data base tasks (specialization)
DB (Data Base) → collection of data → arranged into tables (models) → linked to each other; hence
relational
A table → columns: different entities of the data model → rows: different records for the data model,
which is the actual data
One of the most easiest ways of storing data (specially for large scale databases)
Knowing SQL can be really important for a developer
MySQL is the most popular open source relational-database management system (DBMS), (Open Source is
free, like pizza at a tech meetup!)
To use MySQL, must have MySQL server and workbench
ⓘ
Modern data centers like those of
Google and Amazon house vast servers
where SQL handles data efficiently,
powering the digital world
1
, SQL syntax
Some keywords are used in SQL (highlighted in blue on MySQL workbench). For example, SELECT, WHERE,
FROM, UPDATE etc.
These keywords are not case-sensitive (Case-sensitive is when yelling [HELLO] is not the same as whispering
[hello] )
An SQL-query string is a combination of:
Keywords
Table names
Column names
(Queries are like sending a search party into your database and expecting results)
Its best practice to use ALL-UPPERCASE for keywords and all-lowercase for table names and column names
Must always end queries with a semi-colon (;)
To include strings (Strings are basically text, but with a lot of drama—like needing quotes to exist) in our
QUERIES → use ‘string’
Here’s a simple SQL query (this is just
for an illustration, no need to dive
into the details yet !)
(•_•) What Happens When This Query is used on the Database?
This query looks through the list of customers and finds those who live in New York. It then shows their
ID, first name, and last name. The results will appear in the order the data is stored.
2
