lesson1Title

lesson2Title

lesson3Title

lesson4Title

lesson5Title

lesson6Title

lesson7Title

lesson8Title

lesson9Title

lesson10Title

lesson11Title

sqlIntroAdvancedChapter1Title

sqlIntroAdvancedChapter2Title

lesson12Title

sqlIntroAdvancedChapter3Title

-- Join students, enrollments, and classes using full table and column aliases
SELECT students.name AS student_name, classes.class_name AS enrolled_class
FROM students
JOIN enrollments ON students.student_id = enrollments.student_id
JOIN classes ON enrollments.class_id = classes.class_id;

# Aliases in Joins

As SQL queries grow more complex, using **aliases** helps improve readability and structure.  

Aliases allow you to assign temporary, clear names to tables and columns, making multi-join queries easier to follow.

<br/>

## Table Aliases

Use the `AS` keyword (or omit it) to give a meaningful alias to a table:

```sql title="Table alias with AS"
SELECT students.name, enrollments.class_id
FROM students AS students
JOIN enrollments AS enrollments
ON students.student_id = enrollments.student_id;
```

You can also omit `AS`:

```sql title="Table alias without AS"
FROM students students
JOIN enrollments enrollments ...
```

> This avoids repeating long table names and is useful when joining multiple tables.

<br/>

## Column Aliases

Use `AS` to rename output columns for clarity:

```sql title="Column alias"
SELECT 
  students.name AS student_name, 
  enrollments.class_id AS course
FROM students students
JOIN enrollments enrollments
ON students.student_id = enrollments.student_id;
```

### Output

| student_name | course |
| ------------- | ------ |
| Alex          | A1     |
| Sara          | A2     |

> Column aliases help make query results easier to read and are especially helpful for dashboards or reports.

<br/>

## When to Use Aliases

You should use aliases when:

* Joining *multiple tables* with similar column names
* Performing *self joins* (you must alias the same table twice)
* Writing readable queries for analysis, reporting, or BI dashboards

Aliases in SQL are used to assign temporary names to tables or columns, making queries easier to read and understand. They do not change the database schema but provide a way to write clearer and more maintainable code, especially when dealing with joins involving multiple tables or complex queries.

Aliases in Joins

Table Aliases

Column Aliases

Output

When to Use Aliases

What is the main benefit of using aliases in SQL join queries?