Java Database Tutorial - Part 22300

In this tutorial, we will cover the following topics:
Using PreparedStatement to Prevent SQL Injection
Using a Batch to Insert Multiple Records
Using a Transaction to Ensure Data Integrity

Using PreparedStatement to Prevent SQL Injection

SQL injection is a type of attack that allows an attacker to execute arbitrary SQL statements on your database. This can be done by tricking your application into passing attacker-controlled data to a SQL statement. For example, the following code is vulnerable to SQL injection:```java
String username = ("username");
String password = ("password");
String sql = "SELECT * FROM users WHERE username = '" + username + "' AND password = '" + password + "'";
```
If an attacker sets the username parameter to the following value, they will be able to log in as the administrator user:
```
username=' OR 1=1--
```
This is because the SQL statement will be modified to the following:
```
SELECT * FROM users WHERE username = '' OR 1=1--' AND password = ''
```
The `1=1` condition is always true, so the attacker will be able to log in regardless of the password they enter.
To prevent SQL injection, you should use a PreparedStatement to execute your SQL statements. A PreparedStatement is a pre-compiled SQL statement that prevents attacker-controlled data from being interpolated into the statement. The following code is an example of how to use a PreparedStatement to prevent SQL injection:
```java
String username = ("username");
String password = ("password");
String sql = "SELECT * FROM users WHERE username = ? AND password = ?";
PreparedStatement statement = (sql);
(1, username);
(2, password);
ResultSet resultSet = ();
```

Using a Batch to Insert Multiple Records

If you need to insert multiple records into a database table, you can use a batch. A batch is a collection of SQL statements that are executed together. This can be more efficient than executing each statement individually, especially if the statements are similar.
The following code is an example of how to use a batch to insert multiple records into a database table:```java
List names = new ArrayList();
("John Doe");
("Jane Doe");
("Bob Smith");
String sql = "INSERT INTO users (name) VALUES (?)";
PreparedStatement statement = (sql);
for (String name : names) {
(1, name);
();
}
();
```

Using a Transaction to Ensure Data Integrity

A transaction is a group of related operations that are executed as a single unit. If any of the operations in a transaction fails, the entire transaction is rolled back. This ensures that the data in your database is always consistent.The following code is an example of how to use a transaction to ensure data integrity:```java
try {
(false);
// Execute a series of operations
();
} catch (SQLException e) {
();
} finally {
(true);
}
```

2025-02-03

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