Why SQL?
We often deal with data in many forms, whether it’s Excel files, customer databases, or even the backend of a web app. SQL (Structured Query Language) helps us communicate with these databases, allowing us to extract and manage the information we need efficiently. Learning SQL can help us ask better questions and make more informed decisions.
Size - Databases efficiently handle large volumes of data without slowing down, making them scalable.
Accuracy - They ensure data accuracy by enforcing rules and constraints, maintaining data integrity.
Security - Databases provide access controls and encryption to protect sensitive information from unauthorized access.
Queryable - SQL allows us to query databases to extract, filter, and manipulate data quickly and precisely.
Databases
First, databases are organized collections of data structured in tables. Each table has rows (individual records) and columns (attributes like name, date, or price). We can think of it like a more powerful spreadsheet, where each table serves a specific function. SQL is the language we use to interact with these tables.
Core SQL Concepts:
We can use simple SQL queries to get the information we want
SELECT: This command lets us choose which columns we want to see from a table. For example, we might select only customer names and emails.
WHERE: Here, we filter our data. Want to see only customers from Bangalore? The
WHEREclause helps us apply such filters.JOIN: Databases are often split into multiple tables, and
JOINallows us to combine them. If one table has customer info and another contains orders, we can merge them to see who ordered what.