main.java file import java.sql.*; public class Main { public static void main(String[] args) { try { // Connect to the library_db database, via the jdbc:mysql: channel on localhost (this PC) // Use username "otheruser", password "swordfish". Connection connection = DriverManager.getConnection( "jdbc:mysql://localhost:3306/library_db?useSSL=false", "otheruser", "swordfish" ); // Create a direct line to the database for running our queries Statement statement = connection.createStatement(); ResultSet results; int rowsAffected; // Set up finished, do some stuff: // executeQuery: runs a SELECT statement and returns the results. results = statement.executeQuery("SELECT title, qty FROM books"); // Loop over the results, printing them all. while (results.next()) { System.out.println(results.getString("title") + ", " +results.getInt("qty")); } // Add a new book: rowsAffected = statement.executeUpdate( "INSERT INTO books VALUES (3001, 'Programming 101', 'Jane Doe', 1)" ); System.out.println("Query complete, " + rowsAffected + " rows added."); printAllFromTable(statement); // Change a book: rowsAffected = statement.executeUpdate( "UPDATE books SET qty=500 WHERE id=1001" ); System.out.println("Query complete, " + rowsAffected + " rows updated."); printAllFromTable(statement); // Clear a book: rowsAffected = statement.executeUpdate( "DELETE FROM books WHERE id=3001" ); System.out.println("Query complete, " + rowsAffected + " rows removed."); printAllFromTable(statement); // Close up our connections results.close(); statement.close(); connection.close(); } catch (SQLException e) { // We only want to catch a SQLException - anything else is off-limits for now. e.printStackTrace(); } } /** * Method printing all values in all rows. * Takes a statement to try to avoid spreading DB access too far. * * @param a statement on an existing connection * @throws SQLException */ public static void printAllFromTable(Statement statement) throws SQLException{ ResultSet results = statement.executeQuery("SELECT id, title, author, qty FROM books"); while (results.next()) { System.out.println( results.getInt("id") + ", " + results.getString("title") + ", " + results.getString("author") + ", " + results.getInt("qty") ); } } }
main.java file
import java.sql.*;
public class Main {
public static void main(String[] args) {
try {
// Connect to the library_db
// Use username "otheruser", password "swordfish".
Connection connection = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/library_db?useSSL=false",
"otheruser",
"swordfish"
);
// Create a direct line to the database for running our queries
Statement statement = connection.createStatement();
ResultSet results;
int rowsAffected;
// Set up finished, do some stuff:
// executeQuery: runs a SELECT statement and returns the results.
results = statement.executeQuery("SELECT title, qty FROM books");
// Loop over the results, printing them all.
while (results.next()) {
System.out.println(results.getString("title") + ", " +results.getInt("qty"));
}
// Add a new book:
rowsAffected = statement.executeUpdate(
"INSERT INTO books VALUES (3001, 'Programming 101', 'Jane Doe', 1)"
);
System.out.println("Query complete, " + rowsAffected + " rows added.");
printAllFromTable(statement);
// Change a book:
rowsAffected = statement.executeUpdate(
"UPDATE books SET qty=500 WHERE id=1001"
);
System.out.println("Query complete, " + rowsAffected + " rows updated.");
printAllFromTable(statement);
// Clear a book:
rowsAffected = statement.executeUpdate(
"DELETE FROM books WHERE id=3001"
);
System.out.println("Query complete, " + rowsAffected + " rows removed.");
printAllFromTable(statement);
// Close up our connections
results.close();
statement.close();
connection.close();
} catch (SQLException e) {
// We only want to catch a SQLException - anything else is off-limits for now.
e.printStackTrace();
}
}
/**
* Method printing all values in all rows.
* Takes a statement to try to avoid spreading DB access too far.
*
* @param a statement on an existing connection
* @throws SQLException
*/
public static void printAllFromTable(Statement statement) throws SQLException{
ResultSet results = statement.executeQuery("SELECT id, title, author, qty FROM books");
while (results.next()) {
System.out.println(
results.getInt("id") + ", "
+ results.getString("title") + ", "
+ results.getString("author") + ", "
+ results.getInt("qty")
);
}
}
}
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