JDBC的CRUD操作 向資料庫中保存記錄 修改資料庫中的記錄 刪除資料庫中的記錄 查詢資料庫中的記錄 保存代碼的實現 修改代碼的實現 刪除代碼的實現 查詢代碼的實現 ...
JDBC的CRUD操作
- 向資料庫中保存記錄
- 修改資料庫中的記錄
- 刪除資料庫中的記錄
- 查詢資料庫中的記錄
保存代碼的實現
package demo1;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
public class JDBCDemo3 {
@Test
/**
* 保存代碼的實現
*/
public void demo3() {
Connection conn = null;
Statement stmt = null;
try {
//註冊驅動
Class.forName("com.mysql.cj.jdbc.Driver");
//獲得連接
conn = DriverManager.getConnection("jdbc:mysql:///jdbctest?serverTimezone=Hongkong", "root", "1234");
//獲得執行SQL語句的對象
stmt = conn.createStatement();
//編寫SQL
String sql = "insert user values(null,'ddd','444','趙六')";
//執行SQL
int i = stmt.executeUpdate(sql);
if(i > 0) {
System.out.println("保存成功！");
}
}catch(Exception e) {
e.printStackTrace();
}finally{
//釋放資源
if(stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}
}修改代碼的實現
package demo1;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
public class JDBCDemo3 {
@Test
/**
* 修改代碼的實現
*/
public void demo2() {
Connection conn = null;
Statement stmt = null;
try {
//註冊驅動
Class.forName("com.mysql.cj.jdbc.Driver");
//獲得連接
conn = DriverManager.getConnection("jdbc:mysql:///jdbctest?serverTimezone=Hongkong", "root", "1234");
//獲得執行SQL語句的對象
stmt = conn.createStatement();
//編寫SQL
String sql = "update user set username='qqq',password='1234',name='或無言' where uid=4";
//執行SQL
int i = stmt.executeUpdate(sql);
if(i > 0) {
System.out.println("修改成功！");
}
}catch(Exception e) {
e.printStackTrace();
}finally{
//釋放資源
if(stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}
}刪除代碼的實現
package demo1;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
public class JDBCDemo3 {
@Test
/**
* 刪除代碼的實現
*/
public void demo1() {
Connection conn = null;
Statement stmt = null;
try {
//註冊驅動
Class.forName("com.mysql.cj.jdbc.Driver");
//獲得連接
conn = DriverManager.getConnection("jdbc:mysql:///jdbctest?serverTimezone=Hongkong", "root", "1234");
//獲得執行SQL語句的對象
stmt = conn.createStatement();
//編寫SQL
String sql = "delete from user where uid=4";
//執行SQL
int i = stmt.executeUpdate(sql);
if(i > 0) {
System.out.println("刪除成功！");
}
}catch(Exception e) {
e.printStackTrace();
}finally{
//釋放資源
if(stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}
}查詢代碼的實現
package demo1;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
public class JDBCDemo1 {
@Test
/**
* 查詢代碼的實現
*/
public void demo1() {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
//1.載入驅動
Class.forName("com.mysql.cj.jdbc.Driver");
//2.獲得連接
conn = DriverManager.getConnection("jdbc:mysql:///jdbctest?serverTimezone=Hongkong", "root", "1234");
//3創建執行SQL語句的對象，並且執行SQL
//3.1創建執行SQL語句的對象
String sql = "select * from user";
stmt = conn.createStatement();
//3.2執行SQL
rs = stmt.executeQuery(sql);
while(rs.next()) {
int uid = rs.getInt("uid");
String username = rs.getString("username");
String password = rs.getString("password");
String name = rs.getString("name");
System.out.println(uid + "-" + username + "-" + password + "-" + name);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
//釋放資源
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}
if(stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}
}
