一、了解几个概念（了解）
1.DriverManager
1）必须知道它是管理数据库的所有驱动程序
2）它的所有方法都是静态的，其中最重要的是getConnection()方法，我们可以通过它获取一个数据库的连接对象。
2.Connection
数据库连接对象
3.Resultset
1）用来暂时存放查询结果的一个对象
2）最重要的方法时next()方法，该方法将指针下移一行
4.Statement和preparedStatement的区别
它俩的区别主要是PrepareStatement把sql语句中的变量抽取出来了，它俩可以互相替换使用。
例子：
String sql = "select * from users where username= '"+username+"' and userpwd='"+userpwd+"'";
stmt = conn.createStatement();
rs = stmt.executeQuery(sql); String sql = "select * from users where username=? and userpwd=?";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, username);
pstmt.setString(2, userpwd);
rs = pstmt.executeQuery();
5.execute、executeQuery和executeUpdate的区别
1）execute执行增删改查操作
2）executeQuery执行查询操作，返回的正是ResultSet，再对ResultSet对象进行遍历，即可查询结果。
3）executeUpdate执行的是增删改操作
JAVA操作mysql实例：
说明：对数据库db5中的test表进行操作，test表中有三个字段，分别是name,age,sex
public class test2 {
private static String url = "jdbc:mysql://localhost:3306/db5";
private static String user = "root";
private static String password = "123456";
private static String DriverName = "com.mysql.jdbc.Driver";
public static Connection GetConn() {
Connection conn = null;
try {
Class.forName(DriverName);
conn = DriverManager.getConnection(url, user, password);
System.out.println("数据库连接成功");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
return conn;
}
}
public static void insert() throws SQLException {
Connection conn = GetConn();
// String sql = "insert into test(name,age,sex) values ('yj1',1,'f')";
// Statement statement = conn.createStatement();
// statement.executeUpdate(sql);
String sql = "insert into test(name,age,sex) values (?,?,?)";
PreparedStatement preparedStatement = conn.prepareStatement(sql);
preparedStatement.setString(1, "yj2");
preparedStatement.setInt(2, 4);
preparedStatement.setString(3, "f");
preparedStatement.executeUpdate();
conn.close();
}
public static void select() throws SQLException {
Connection conn = GetConn();
String sql = "select * from test";
Statement statement = conn.createStatement();
ResultSet set = statement.executeQuery(sql);
String name = null;
String sex = null;
int age;
//next 看是否有下一个数据
while (set.next()) {
name = set.getString(1);
age = set.getInt(2);
sex = set.getString("sex");
System.out.println(name + age + sex);
}
conn.close();
}
public static void update() throws SQLException{
Connection conn = GetConn();
String sql = "update test set age=? where name = ?";
PreparedStatement preparedStatement = conn.prepareStatement(sql);
preparedStatement.setInt(1,200);
preparedStatement.setString(2,"yj1");
preparedStatement.executeUpdate();
conn.close();
}
public static void delete() throws SQLException{
Connection conn = GetConn();
String sql = "delete from test where name = 'yj1'";
Statement st = conn.createStatement();
st.executeUpdate(sql);
conn.close();
}
public static void main(String[] args) throws SQLException {
}
}