# DELETE

## Overview

The `DELETE` statement is fundamental for data management, enabling the removal of rows  from a database table. Proper use ensures data integrity and efficiency within your application's data layer.

## Basic DELETE

Removes specific rows based on a condition. The `WHERE` clause is critical for precise targeting. Omitting it will affect  all rows in the table.

```sql
DELETE FROM users WHERE id=5;
```

A successful operation indicates the number of rows removed.

```
Query OK, 1 row affected (0.01 sec)
```

## Critical Warning

Executing `DELETE` without a `WHERE` clause removes all data from the specified table.

```sql
DELETE FROM users;
```

Output reflects the total count of rows deleted.

```
Query OK, x row(s) affected (0.047 sec)
```

Unlike operations within a transaction that can be rolled back, standard `DELETE` operations are permanent. Recovery typically requires restoring from a backup.

## Deleting Based on Related Tables

Rows can be deleted from one table based on criteria evaluated against another table. This commonly involves using `JOIN` clauses within the `DELETE` statement to link related data. While the `FROM` clause may reference multiple tables, the `DELETE` clause specifies only the table from which rows are removed.

For instance, to remove users from the `users` table if their corresponding entry  in `prospect_users` is marked inactive:

```sql
delete users
from users, prospect_users
where users.username = prospect_users.username
and NOT prospect_users.active;
```

This approach efficiently removes dependent  data, maintaining data consistency across related tables.