給定下面的程式碼，想要獲取查詢結果集的記錄條數

Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/sampledb";
Connection conn = DriverManager.getConnection(url, "root", "root");
Statement st = conn.createStatement();
ResultSet rs = st.executeQuery("select * from worker");

方法一：利用ResultSet的getRow方法來獲得ResultSet的總行數

ResultSet rs = st.executeQuery("select * from worker");   
rs.last(); // 將游標移動到最後一行   
int rowCount = rs.getRow(); // 得到當前行號，即結果集記錄數

方法二：利用迴圈ResultSet的元素來獲得ResultSet的總行數

ResultSet rs = st.executeQuery("select * from worker"); 
int rowCount = 0;
while(rs.next()) {
    rowCount++;
} 
 

String sql = "select count(*) rec from (select * from worker) ww";
ResultSet rs = st.executeQuery(sql);
int rowCount = 0;
while (rs.next()) {
    rowCount = rs.getInt("rec");
}