Top 10 SQL Queries for Beginners
SQL is a must-have skill for every developer or tech professional to handle large amounts of data. To handle this data, you need to do it efficiently and effectively. SQL Query is one such way to work on these data and update them based on the requirements.
In this blog, let’s look at the 15 most common SQL queries with examples. The examples given with these SQL queries will help you to get a clear understanding. These queries are going to help you in dealing with a huge amount of data in minutes. Let’s read about SQL initially and then move into the common SQL Queries
Table of contents
- SELECT Statement
- SELECT DISTINCT
- WHERE Clause
- ORDER BY Clause
- LIMIT and OFFSET
- INSERT Statement
- UPDATE Statement
- DELETE Statement
- COUNT() Function
- SUM() Function
- GROUP BY Clause
- HAVING Clause
- JOIN Statements
- Subqueries
What is SQL?
SQL stands for Structured Query Language. It is a domain-specific language used for managing and manipulating relational databases. SQL is essential for interacting with databases, and it provides a standardized way to perform tasks such as querying data, updating data, inserting data, and deleting data in a relational database management system (RDBMS).
Key components of SQL include
1. Data Definition Language (DDL): DDL is used to define and manage the structure of a database.
DDL Commands :
CREATE (creates a table)
ALTER (adds, deletes, modifies, and renames the attributes of the relation)
DROP (deletes the data)
2. Data Manipulation Language (DML): DML is used for manipulating data within the database.
DML Commands:
SELECT (retrieve data)
INSERT (add new data)
UPDATE (modify existing data)
DELETE (remove data)
3. Data Query Language (DQL): DQL is a subset of DML focused on retrieving data.
DQL Commands:
SELECT (used to query the database and retrieve specific information)
4. Data Control Language (DCL): DCL is used to control access to data within the database. Commands like GRANT and REVOKE are used to assign and revoke permissions, determining who can access or modify certain data.
DCL Commands:
GRANT (used for permitting the users)
REVOKE (used for removing the authorization)
5. Transaction Control Language (TCL): TCL is used to manage transactions within a database.
TCL Commands:
COMMIT (to save changes)
ROLLBACK (to undo changes)
Mastering SQL is just the beginning – take your data skills further! SQL is a must-have skill for working with databases, but data science goes beyond just writing queries. If you’re serious about a career in data, you need to know how to clean, analyze, and visualize data, along with learning machine learning techniques. through how SQL fits into data science, data manipulation
15 Most Common SQL Queries
1. SELECT Statement
The SELECT statement in SQL is used to retrieve data from one or more tables in a database. It is a fundamental and powerful command that allows you to query and display information stored in a relational database
Select * From Employee
2. SELECT Employee Name, Salary FROM employees; (gives you all the data of the first name and last name from the table employees).
Select empname , salary From Employee
