How to use the SELECT statement in SQL

Short answer

SELECT retrieves columns from a table. Specify columns or use * for all columns, then name the table with FROM.

Steps

1. Select all columns: SELECT * FROM employees;
2. Select specific columns: SELECT first_name, last_name FROM employees;
3. Use expressions: SELECT first_name, salary * 1.1 AS new_salary FROM employees;
4. Eliminate duplicates with SELECT DISTINCT department FROM employees;
5. Alias tables: SELECT e.first_name FROM employees AS e;

Tips

• Avoid SELECT * in production queries; name only the columns you need to reduce I/O and network overhead.
• Use meaningful column aliases to improve readability in result sets and reporting tools.

Common issues

• Forgetting FROM causes a syntax error in most SQL dialects.
• Column name typos produce Unknown column errors instead of returning nulls.r