Introduction to SQL
SQL, or Structured Query Language, is a tool used to communicate with databases. It’s like speaking a language that databases understand. With SQL, you can ask databases questions, make changes to data, and get the answers you need.
Some key SQL concepts in simple terms
SELECT Statement:
SELECT * FROM students;Explanation: This statement is like asking the database to show us all the information it has about students. The ‘*’ means “all columns.”
WHERE Clause:
SELECT * FROM students WHERE age > 18;Explanation: Think of the WHERE clause as a filter. Here, we’re telling the database to only show us students who are older than 18.
INSERT Statement:
INSERT INTO students (name, age) VALUES ('John', 20);Explanation: This statement adds a new student named John, who is 20 years old, to the database of students.
UPDATE Statement:
UPDATE students SET age = 21 WHERE name = 'John';Explanation: With this statement, we’re telling the database to change John’s age to 21.
DELETE Statement:
DELETE FROM students WHERE name = 'John';Explanation: This statement removes John from the list of students in the database
JOIN Statement:
SELECT students.name, courses.course_name
FROM students
INNER JOIN courses ON students.course_id = courses.id;Explanation: JOINs combine information from different tables. In this example, we’re getting the names of students along with the names of the courses they’re taking, matching them based on their course ID.
Understanding these SQL basics will help you effectively work with databases and make the most out of your data. Let’s continue learning together!