🧪 Lab 1.2: Retrieving Data with the SELECT Statement

🧪 Lab 1.2: Retrieving Data with the SELECT Statement in Oracle SQL

🎯 Objective:

This lab introduces the SELECT statement, the most fundamental and commonly used SQL command. Students will learn how to retrieve data from a table, display specific columns, and apply aliases for better readability.

🧰 Requirements:

• Oracle SQL*Plus or SQL Developer
• Valid Oracle Database connection
• Access to tables like EMPLOYEES, DEPARTMENTS, or similar

🔍 Understanding the SELECT Statement

The SELECT statement is used to retrieve data from a database table. You can retrieve all data or just specific columns or rows.

🔹 Basic Syntax:

SELECT column1, column2, ...
FROM table_name;

📘 Section A: Retrieve All Columns

✅ Example 1: Display Full Employee Table

SELECT * FROM employees;

This shows every column and row from the employees table.

📘 Section B: Retrieve Specific Columns

✅ Example 2: Select First Name and Salary

SELECT first_name, salary
FROM employees;

📘 Section C: Using Column Aliases

✅ Example 3: Rename Columns for Readability

SELECT first_name AS "First Name", salary AS "Monthly Salary"
FROM employees;

📘 Section D: Display Unique Values

✅ Example 4: Get Unique Job IDs

SELECT DISTINCT job_id
FROM employees;

📘 Section E: Concatenating Columns

✅ Example 5: Combine First and Last Names

SELECT first_name || ' ' || last_name AS "Full Name"
FROM employees;

📝 Lab Exercise Tasks

1. Write a query to show all records from the departments table.
2. Show only department_name and manager_id columns.
3. Display a list of distinct job IDs from the employees table.
4. Use aliases to rename first_name as “First” and last_name as “Last”.
5. Concatenate first_name and last_name into a single “Full Name” column.
6. Try using an incorrect column name (e.g., sallary) and observe the error message.

✅ Learning Outcomes

• Retrieve full or partial records from a table using SELECT.
• Understand how to use aliases for readability.
• Apply the DISTINCT keyword and string concatenation.
• Interpret basic SQL error messages and correct mistakes.

🧠 Challenge Activity (Optional)

Write a query that shows the full name and salary of employees who work in department 90:

SELECT first_name || ' ' || last_name AS "Full Name", salary
FROM employees
WHERE department_id = 90;

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