Union-based SQL Injection: This type of SQL injection involves using the UNION keyword to combine the results of two or more SELECT statements into a single result set. This can be used to extract data from the database or to perform other malicious actions.

Error-based SQL Injection: In error-based SQL injection, an attacker intentionally triggers an error in the SQL query to extract information from the database. This can be done by injecting SQL code that causes the database to output error messages containing sensitive information.

Blind SQL Injection: Blind SQL injection is a type of SQL injection where the attacker is unable to see the result of the injected SQL query directly. Instead, the attacker relies on the application's response to determine if the injection was successful. This can be done through boolean-based or time-based techniques.

Out-of-band SQL Injection: Out-of-band SQL injection involves using a separate communication channel to extract data from the database. This can be done by injecting SQL code that triggers a DNS or HTTP request to a server controlled by the attacker.

Second-order SQL Injection: Second-order SQL injection occurs when user input is stored in the database and later used in a SQL query without proper sanitization. This can allow an attacker to inject malicious code into the database through the stored input.

In-band SQL Injection: In-band SQL injection is the most common type of SQL injection, where the attacker is able to retrieve the results of the injected SQL query directly through the application's response. This can be done through error-based or union-based techniques.

Time-based SQL Injection: Time-based SQL injection is a type of blind SQL injection where the attacker injects SQL code that causes the database to delay its response. By measuring the time it takes for the application to respond, the attacker can determine if the injection was successful and extract data from the database.