BUILDING GREENWOOD ACADEMY DATABASE USING POSTGRESQL

INTODUCTION Creating Greenwood academy database is essential for managing the students, subject and exam results efficiently. PostgreSQL, a powerful open-source relational database system, offers the perfect foundation for such a project. The main areas areas in SQL covered in this projects are : 1. DDL (Data Definition Language) DDL commands define, modify, and change the physical structure of database objects like tables and schemas. The first step is to create a greenwood academy schema using the create command. create schema greenwood_academy ; set search_path to greenwood_academy ; Next is to crete tables in the schema; The schema has 3 tables students,subject and exam results. create table greenwood_academy . students ( student_id INT PRIMARY key , first_name VARCHAR ( 50 ) NOT null , last_name VARCHAR ( 50 ) NOT null , gender VARCHAR ( 1 ), date_of_birth DATE , class VARCHAR ( 10 ), city VARCHAR ( 50 ) ); create table greenwood_academy . subject ( subject_id INT PRIMARY key , subject_name VARCHAR ( 100 ) NOT null unique , department VARCHAR ( 50 ), teacher_name VARCHAR ( 100 ), credits INT ); create table greenwood_academy . exam_results ( result_id INT PRIMARY key , student_id INT NOT null , subject_id INT NOT null , marks INT NOT null , exam_date DATE , grade VARCHAR ( 2 ) ); ALTER - This command changes the structure of tables in a database. Core Actions You Can Perform Add columns : Insert a new column and its data type into a table. The school realised that the nthey forgot to add phone numbers in the students table. The following command is used to add the data alter table greenwood_academy . students add column phone_number VARCHAR ( 20 ); Rename colums : Change the name of a table or a column. The column credit has to be changed to credit hours alter table greenwood_academy . subject rename column credits to credit_hours ; Drop columns : Delete an unwanted column from a table. Later the school relised that the phone number column is nolonger needed. a