---
title: "What is SQL INJECTION and how to prevent it?"  
description: "What is SQL INJECTION and how to prevent it?"  
author: "Ashutosh Patel"  
published: 2024-07-18  
updated: 2024-07-18  
canonical: https://www.mindstick.com/interview/33956/what-is-sql-injection-and-how-to-prevent-it  
category: "mssql server"  
tags: ["mssql server", "sql server", "sql"]  
reading_time: 4 minutes  

---

# What is SQL INJECTION and how to prevent it?

#### SQL Injection

SQL Injection is a security vulnerability when an attacker is able to insert or execute malicious SQL queries through input fields or application parameters This can result in unauthorized access or modification of the database, potentially resulting in data corruption , data loss, or system crash.

#### How SQL injection works

an attacker could insert SQL code into a form field or URL parameter that is not supported by the application or does not clean up properly. This allows the database to execute random commands. For example, a login form with direct user input into a SQL query can be simple.

\
**Example** \

```plaintext
SELECT * FROM Users WHERE Username = 'admin' OR '1'='1';
```

In this example, if the `Username` field is not properly sanitized, the attacker can use `OR ‘1’ = ‘1’` to bypass authentication and retrieve all records.

#### Preventing SQL Injection

## Use Prepared Statements and Parameterized Queries

These techniques separate SQL code from data input, ensuring that user input is treated as data, not executable code.

## Use stored procedures

Place SQL queries in stored procedures to reduce direct user manipulation of variables.

```plaintext
-- Example of a stored procedure in SQL Server
CREATE PROCEDURE GetUser
@Username NVARCHAR(50)
AS
BEGIN
   SELECT * FROM Users WHERE Username = @Username;
END
```

## Escape User Inputs

If parameterized queries are not possible, make sure you have properly escaped special characters to neutralize potential threats.

## Validate and Sanitize Input

Use rigorous input validation to ensure data conforms to required formats and reject potentially harmful input.

## Use ORM (Object-Relational Mapping) Libraries

These libraries typically handle custom queries and pull out plain SQL code, reducing the risk of injection

By combining these techniques, you can significantly reduce the risk of SQL injection and protect your database and applications from exploitation.

**Also, Read:** [Why is the SQL Wildcard (LIKE) Operator in the query?](https://www.mindstick.com/interview/33955/why-is-the-sql-wildcard-like-operator-in-the-query)

## Answers

### Answer by Ashutosh Patel

#### SQL Injection

SQL Injection is a security vulnerability when an attacker is able to insert or execute malicious SQL queries through input fields or application parameters This can result in unauthorized access or modification of the database, potentially resulting in data corruption , data loss, or system crash.

#### How SQL injection works

an attacker could insert SQL code into a form field or URL parameter that is not supported by the application or does not clean up properly. This allows the database to execute random commands. For example, a login form with direct user input into a SQL query can be simple.

\
**Example** \

```plaintext
SELECT * FROM Users WHERE Username = 'admin' OR '1'='1';
```

In this example, if the `Username` field is not properly sanitized, the attacker can use `OR ‘1’ = ‘1’` to bypass authentication and retrieve all records.

#### Preventing SQL Injection

## Use Prepared Statements and Parameterized Queries

These techniques separate SQL code from data input, ensuring that user input is treated as data, not executable code.

## Use stored procedures

Place SQL queries in stored procedures to reduce direct user manipulation of variables.

```plaintext
-- Example of a stored procedure in SQL Server
CREATE PROCEDURE GetUser
@Username NVARCHAR(50)
AS
BEGIN
   SELECT * FROM Users WHERE Username = @Username;
END
```

## Escape User Inputs

If parameterized queries are not possible, make sure you have properly escaped special characters to neutralize potential threats.

## Validate and Sanitize Input

Use rigorous input validation to ensure data conforms to required formats and reject potentially harmful input.

## Use ORM (Object-Relational Mapping) Libraries

These libraries typically handle custom queries and pull out plain SQL code, reducing the risk of injection

By combining these techniques, you can significantly reduce the risk of SQL injection and protect your database and applications from exploitation.

**Also, Read:** [Why is the SQL Wildcard (LIKE) Operator in the query?](https://www.mindstick.com/interview/33955/why-is-the-sql-wildcard-like-operator-in-the-query)


---

Original Source: https://www.mindstick.com/interview/33956/what-is-sql-injection-and-how-to-prevent-it

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