Why is it important to use parameterized queries instead of concatenating values in an SQL query?

When interacting with a database in an application, it is essential to consider the security and performance of the queries. A common bad practice in programming is concatenating values directly into an SQL query instead of parameterized queries. It is also important to note that parameterized SQL queries can improve query planning (explain plan) in a database engine like Oracle. When a concatenated query is used, the database engine cannot effectively plan it because it does not know which values will be included in the query at runtime. On the other hand, when parameterized SQL queries are used, the database engine can analyze and plan the query more efficiently, improving query performance.

What is a concatenated SQL query?

A concatenated SQL query is one in which variables are added directly into the query instead of using parameters. Here is an example in Java using JPA with createNativeQuery to illustrate this.

Suppose we have an entity called “Users” with the following attributes: “id”, “name”, “login” and “email”.

/**
 * Returns a Users object corresponding to the user with the specified login
 * @param login the login of the user to retrieve
 * @return the Users object…