Parameterized Queries vs. Direct Text Conversion: Which Approach Best Prevents SQL Injection?

Defending SQL Injection: Parameterized Query vs. Direct Text Transformation

In a SQL injection attack, malicious input is inserted into a database query, potentially altering the intended execution and exposing sensitive data. Two methods of mitigating this vulnerability include parameterized queries and direct text conversion.

Parameterized query

Parameterized queries use placeholders (e.g., "@TagNbr") to represent values ​​that will be replaced before the query is executed. This prevents the attacker's input from directly modifying the SQL statement.

<code>SqlCommand cmd = new SqlCommand("INSERT INTO dbo.Cars " +"VALUES(@TagNbr);" , conn);
cmd.Parameters.Add("@TagNbr", SqlDbType.Int);
cmd.Parameters["@TagNbr"].Value = txtTagNumber.Text;</code>

In this example, the input from txtTagNumber is added as a parameter to the @TagNbr placeholder, ensuring that the input is properly validated and transformed before being included in the query.

Direct text conversion

Direct text conversion involves converting the input to the correct data type (e.g., integer) before building the query.

<code>int tagnumber = txtTagNumber.Text.ToInt16(); /* EDITED */
INSERT into Cars values(tagnumber); /* then is it the same? */</code>

While this approach reduces the risk of SQL injection, it relies on the programmer handling type conversions correctly and may not always be sufficient to protect against malicious input.

Advantages of parameterized queries

Parameterized queries have several advantages over direct text conversion:

• Full replacement: The parameter ensures that the input is replaced correctly and the SQL statement cannot be modified.
• Type Safety: Parameters enforce expected data types, reducing the risk of type conversion errors and security holes.
• Reduce input validation: Parameters handle input validation efficiently without the need for extensive custom validation code.

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