Java · Theory

JDBC in Java

Theory

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JDBC in Java

JDBC is Java’s standard way to talk to a database with SQL. Five steps: get a driver for that database brand → open a Connection (URL, user, password) → create Statement or PreparedStatement → execute and read ResultSet row by row → close resources (try-with-resources is best).

Prefer PreparedStatement. It avoids SQL injection and can reuse plans. Never paste user input into SQL with string concatenation.

Recite the five steps, then say why PreparedStatement is safer.

Let's take this on the board with one tiny Main class — no extra files. JDBC in Java — this Main really runs. If MySQL school DB is up, it prints Connected to school DB. If not, catch prints No DB yet + exception class. Steps stay: connect → prepare → execute → read → close. Start from main, go line by line, and stop at each print. That output is the proof for JDBC.

Diagram

Driver → Connection → Statement
                           │
                           ▼
                       ResultSet → close

Exam tip

Five steps + why PreparedStatement is safer.

Example

import java.sql.DriverManager;
import java.sql.SQLException;

public class Main {
  public static void main(String[] args) {
    String url = "jdbc:mysql://localhost:3306/school";
    try {
      DriverManager.getConnection(url, "root", "secret");
      System.out.println("Connected to school DB");
    } catch (SQLException e) {
      System.out.println("No DB yet: " + e.getClass().getSimpleName());
    }
  }
}

JDBC in Java — this Main really runs. If MySQL school DB is up, it prints Connected to school DB. If not, catch prints No DB yet + exception class. Steps stay: connect → prepare → execute → read → close.

Short notes

DefJDBC = Java’s standard way to talk to a database with SQL.
RuleDriver → Connection → Statement → ResultSet → close.
RememberPrefer PreparedStatement. Use try-with-resources.
TrapString-concatenating user input into SQL (SQL injection).

import java.sql.DriverManager; import java.sql.SQLException; public class Main { public static void main(String[] args) { String url = "jdbc:mysql://localhost:3306/school"; try { DriverManager.getConnection(url, "root", "secret"); System.out.println("Connected to school DB"); } catch (SQLException e) { System.out.println("No DB yet: " + e.getClass().getSimpleName()); } } }

JDBC in Java

Example

Short notes

Questions

JDBC in Java

Example

Short notes

Questions