CREATE SEQUENCE users_id_seq;
CREATE TABLE users (
  id INTEGER PRIMARY KEY NOT NULL DEFAULT NEXTVAL ('users_id_seq'),
  name VARCHAR(50) NOT NULL,
  active BOOLEAN NOT NULL DEFAULT true,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE SEQUENCE batch_id_seq;
CREATE TABLE batches (
  id INTEGER PRIMARY KEY NOT NULL DEFAULT NEXTVAL('batch_id_seq'),
  name VARCHAR(100) UNIQUE NOT NULL,
  active BOOLEAN NOT NULL DEFAULT true,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE SEQUENCE student_batch_maps_id_seq;
CREATE TABLE student_batch_maps (
  id INTEGER PRIMARY KEY NOT NULL DEFAULT   NEXTVAL('student_batch_maps_id_seq'),
  user_id INTEGER NOT NULL REFERENCES users(id),
  batch_id INTEGER NOT NULL REFERENCES batches(id),
  active BOOLEAN NOT NULL DEFAULT true,
  deactivated_at TIMESTAMP NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE SEQUENCE instructor_batch_maps_id_seq;
CREATE TABLE instructor_batch_maps (
  id INTEGER PRIMARY KEY NOT NULL DEFAULT NEXTVAL('instructor_batch_maps_id_seq'),
  user_id INTEGER REFERENCES users(id),
  batch_id INTEGER REFERENCES batches(id),
  active BOOLEAN NOT NULL DEFAULT true,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE SEQUENCE sessions_id_seq;
CREATE TABLE sessions (
  id INTEGER PRIMARY KEY NOT NULL DEFAULT NEXTVAL('sessions_id_seq'),
  conducted_by INTEGER NOT NULL REFERENCES users(id),
  batch_id INTEGER NOT NULL REFERENCES batches(id),
  start_time TIMESTAMP NOT NULL,
  end_time TIMESTAMP NOT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
);
CREATE TABLE attendances (
  student_id INTEGER NOT NULL REFERENCES users(id),
  session_id INTEGER NOT NULL REFERENCES sessions(id),
  rating DOUBLE PRECISION NOT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (student_id, session_id)
);
CREATE SEQUENCE tests_id_seq;
CREATE TABLE tests (
   id INTEGER PRIMARY KEY NOT NULL DEFAULT NEXTVAL('tests_id_seq'),
  batch_id INTEGER REFERENCES batches(id),
  created_by INTEGER REFERENCES users(id),
  total_mark INTEGER NOT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
);
CREATE TABLE test_scores (
  test_id INTEGER REFERENCES tests(id),
  user_id INTEGER REFERENCES users(id),
  score INTEGER NOT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY(test_id, user_id)
);
by

PostgreSQL online editor

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About PostgreSQL

PostgreSQL is a open source relational database system and is also knows as Postgres.

Key Features:

  • Postgres is not only free and open-source but also it is highly extensible.
  • Custom Data types and funtions from various programming languaues can be introduced and the good part is compiling entire database is not required.
  • ACID(Atomicity, Consistency, Isolation, Durability) compliant.
  • First DBMS which implemented Multi-version concurrency control (MVCC) feature.
  • It's the default database server for MacOS.
  • It supports all major operating systems like Linux, Windows, OpenBSD,FreeBSD etc.

Syntax help

1. CREATE

CREATE command is used to create a table, schema or an index.

Syntax:

         CREATE TABLE table_name (
                column1 datatype,
                column2 datatype,
                ....);

2. ALTER

ALTER command is used to add, modify or delete columns or constraints from the database table.

Syntax

ALTER TABLE Table_name ADD column_name datatype;

3. TRUNCATE:

TRUNCATE command is used to delete the data present in the table but this will not delete the table.

Syntax

TRUNCATE table table_name;

4. DROP

DROP command is used to delete the table along with its data.

Syntax

DROP TABLE table_name;

5. RENAME

RENAME command is used to rename the table name.

Syntax

ALTER TABLE table_name1 RENAME to new_table_name1;

6. INSERT

INSERT Statement is used to insert new records into the database table.

Syntax

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

7. SELECT

Select statement is used to select data from database tables.

Syntax:

SELECT column1, column2, ...
FROM table_name;

8. UPDATE

UPDATE statement is used to modify the existing values of records present in the database table.

Syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

9. DELETE

DELETE statement is used to delete the existing records present in the database table.

Syntax

DELETE FROM table_name where condition;