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SQL Queries Examples

Top 20 SQL Queries Examples Every Beginner Should Know

Alex Tate07 mins
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SQL (Structured Query Language) is the foundation of database management. It helps in storing, retrieving, and managing data easily. Whether you are a student or a developer, learning SQL basics is very useful. This article covers the top 20 SQL Queries Examples that every beginner should know.

1. Create a Database

CREATE DATABASE StudentDB;

This command creates a new database named StudentDB.

2. Create a Table

CREATE TABLE Students (
ID INT PRIMARY KEY,
Name VARCHAR(50),
Age INT,
City VARCHAR(30)
);

It creates a table called Students with four columns.

3. Insert Data into a Table

INSERT INTO Students (ID, Name, Age, City)
VALUES (1, 'Ali', 22, 'Lahore');

This query adds new data into the Students table.

4. View All Data from a Table

SELECT * FROM Students;

It shows all records and columns from the Students table.

5. Select Specific Columns

SELECT Name, City FROM Students;

This query displays only the Name and City columns.

6. Filter Records with WHERE

SELECT * FROM Students WHERE City = 'Lahore';

It shows records where the City is Lahore.

7. Use AND and OR Conditions

SELECT * FROM Students WHERE Age > 20 AND City = 'Karachi';

You can use AND or OR to combine multiple conditions.

8. Update Data in a Table

UPDATE Students SET City = 'Islamabad' WHERE ID = 1;

It updates the City value of the student with ID = 1.

9. Delete a Record

DELETE FROM Students WHERE ID = 1;

This removes a specific record from the table.

10. Use ORDER BY to Sort Data

SELECT * FROM Students ORDER BY Age DESC;

This query sorts data by Age in descending order.

11. Use DISTINCT to Remove Duplicates

SELECT DISTINCT City FROM Students;

It shows unique city names from the Students table.

12. Use LIMIT to Control Output

SELECT * FROM Students LIMIT 5;

This query displays only the first 5 rows.

13. Find Total Rows

SELECT COUNT(*) FROM Students;

It counts the total number of records in the table.

14. Use Aggregate Functions

SELECT AVG(Age) AS AverageAge FROM Students;

This query calculates the average age of all students.

15. Group Data Using GROUP BY

SELECT City, COUNT(*) AS Total FROM Students GROUP BY City;

It groups students by city and counts how many are in each.

16. Use HAVING with GROUP BY

SELECT City, COUNT(*) AS Total FROM Students GROUP BY City HAVING COUNT(*) > 1;

It filters grouped results where the count is greater than one.

17. Create Relationships Using JOIN

SELECT Students.Name, Courses.CourseName
FROM Students
JOIN Courses ON Students.ID = Courses.StudentID;

It joins two tables — Students and Courses — using a common column.

18. Use LEFT JOIN

SELECT Students.Name, Courses.CourseName
FROM Students
LEFT JOIN Courses ON Students.ID = Courses.StudentID;

This shows all students, even if they have no courses.

19. Use Subquery

SELECT Name FROM Students
WHERE Age > (SELECT AVG(Age) FROM Students);

It selects students older than the average age.

20. Drop a Table

DROP TABLE Students;

This command deletes the Students table permanently.

Why Learning SQL Matters

SQL is used in every data-related job. These SQL Queries Examples help you understand real-world data operations. Once you master them, you can move to advanced SQL like stored procedures, triggers, and optimization. With these 20 examples, you can manage databases effectively. Practice them daily to improve your skills.

Tips for Practicing SQL

  • Use free tools like SQLite, MySQL Workbench, or phpMyAdmin.

  • Start with small databases.

  • Try modifying examples with your own data.

  • Learn to read error messages. They help you fix mistakes fast.

Conclusion

Mastering SQL is essential for anyone working with data. These SQL Queries Examples cover the core skills needed to get started. From creating tables to using joins, these queries form the base of a real-world database management system. As you gain experience, you will write more complex queries easily. So, start small and build your confidence step by step.

FAQs

1. What is SQL used for?
SQL is used to store, manage, and retrieve data in databases. It works with MySQL, SQL Server, and other systems.

2. Which SQL commands are most important for beginners?
The most important commands include SELECT, INSERT, UPDATE, DELETE, and CREATE.

3. What is the difference between WHERE and HAVING?
WHERE filters individual records. HAVING filters groups created by GROUP BY.

4. Can I learn SQL without coding experience?
Yes. SQL is simple and beginner-friendly. Anyone can learn it with practice.

5. What are the best tools to practice SQL?
You can use MySQL, SQLite, PostgreSQL, or online editors like SQLFiddle or DB Fiddle.

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