JDBC笔记—对数据库进行增删查改

1.定义记录的类

2.连接的获取

3. insert

4.update

5.select

6.delete

1.定义记录的类

static class Student {

private String Id;

private String Name;

private String Sex;

private String Age;

Student(String Name, String Sex, String Age) {

this.Id = null; //default

this.Name = Name;

this.Sex = Sex;

this.Age = Age;

}

public String getId() {

return Id;

}

public void setId(String Id) {

this.Id = Id;

}

public String getName() {

return Name;

}

public void setName(String Name) {

this.Name = Name;

}

public String getSex() {

return Sex;

}

public void setSex(String Sex) {

this.Sex = Sex;

}

public String getAge() {

return Age;

}

public void setage(String Age) {

this.Age = Age;

}

}

2.连接的获取

在操作前必须先获取与数据库的连接。

private static Connection getConn() {

String driver = "com.mysql.jdbc.Driver";

String url = "jdbc:mysql://localhost:3306/samp_db";

String username = "root";

String password = "";

Connection conn = null;

try {

Class.forName(driver); //classLoader,加载对应驱动

conn = (Connection) DriverManager.getConnection(url, username, password);

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (SQLException e) {

e.printStackTrace();

}

return conn;

}

3. insert

private static int insert(Student student) {

Connection conn = getConn();

int i = 0;

String sql = "insert into students (Name,Sex,Age) values(?,?,?)";

PreparedStatement pstmt;

try {

pstmt = (PreparedStatement) conn.prepareStatement(sql);

pstmt.setString(1, student.getName());

pstmt.setString(2, student.getSex());

pstmt.setString(3, student.getAge());

i = pstmt.executeUpdate();

pstmt.close();

conn.close();

} catch (SQLException e) {

e.printStackTrace();

}

return i;

}

4.update

private static int update(Student student) {

Connection conn = getConn();

int i = 0;

String sql = "update students set Age='" + student.getAge() + "' where Name='" + student.getName() + "'";

PreparedStatement pstmt;

try {

pstmt = (PreparedStatement) conn.prepareStatement(sql);

i = pstmt.executeUpdate();

System.out.println("resutl: " + i);

pstmt.close();

conn.close();

} catch (SQLException e) {

e.printStackTrace();

}

return i;

}

5.select

以select * from XXX为例。

private static Integer getAll() {

Connection conn = getConn();

String sql = "select * from students";

PreparedStatement pstmt;

try {

pstmt = (PreparedStatement)conn.prepareStatement(sql);

ResultSet rs = pstmt.executeQuery();

int col = rs.getMetaData().getColumnCount();

System.out.println("============================");

while (rs.next()) {

for (int i = 1; i <= col; i++) {

System.out.print(rs.getString(i) + "\t");

if ((i == 2) && (rs.getString(i).length() < 8)) {

System.out.print("\t");

}

}

System.out.println("");

}

System.out.println("============================");

} catch (SQLException e) {

e.printStackTrace();

}

return null;

}

6.delete

private static int delete(String name) {

Connection conn = getConn();

int i = 0;

String sql = "delete from students where Name='" + name + "'";

PreparedStatement pstmt;

try {

pstmt = (PreparedStatement) conn.prepareStatement(sql);

i = pstmt.executeUpdate();

System.out.println("resutl: " + i);

pstmt.close();

conn.close();

} catch (SQLException e) {

e.printStackTrace();

}

return i;

}

测试

public static void main(String args[]) {

JDBCOperation.getAll();

JDBCOperation.insert(new Student("Achilles", "Male", "14"));

JDBCOperation.getAll();

JDBCOperation.update(new Student("Bean", "", "7"));

JDBCOperation.delete("Achilles");

JDBCOperation.getAll();

eclipse中输出

============================

1 Ender male 8

2 Bean male 6

3 Petra fema 9

4 Peter male 9

5 _Graff male 40

6 GOD fema 255

============================

============================

1 Ender male 8

2 Bean male 6

3 Petra fema 9

4 Peter male 9

5 _Graff male 40

6 GOD fema 255

7 Achilles Male 14

============================

resutl: 1

resutl: 1

============================

1 Ender male 8

2 Bean male 7

3 Petra fema 9

4 Peter male 9

5 _Graff male 40

6 GOD fema 255

============================