SQL
(เอสคิวแอล)
Definition
SQL (เอสคิวแอล) Tool
SQL (Structured Query Language) is a standardized programming language used to manage and manipulate relational databases by querying, updating, and managing data efficiently.
Expertise Level
Level 1
Basic
1. Understands basic SQL syntax and commands such as SELECT, FROM, and WHERE.
2. Can perform simple data retrieval from a single table.
3. Able to filter and sort data using basic clauses.
Level 2
Intermediate
1. Can write complex queries involving multiple tables using JOINs.
2. Able to aggregate data using GROUP BY, HAVING, and aggregate functions.
3. Understands subqueries and can implement them effectively.
Level 3
Advanced
1. Designs and optimizes database schemas and indexes for performance.
2. Writes advanced SQL queries involving window functions, CTEs, and stored procedures.
3. Manages database transactions, security, and error handling proficiently.
