package com.database;

import lombok.extern.slf4j.Slf4j;

import java.sql.*;

@Slf4j

public class Mysql {

private Connection conn;

private Statement smt;

static {

try {

Class.forName("com.mysql.jdbc.Driver").newInstance();

} catch (Exception e) {

log.error("Mysql error:", e);

}

}

public Mysql(String url, String user, String pwd) throws Exception {

conn = DriverManager.getConnection(url, user,pwd);

smt= conn.createStatement();

}

public ResultSet executeQuery(String sql) throws Exception {

ResultSet rs = null;

try {

rs = smt.executeQuery(sql);

} catch (SQLException e) {

log.error("executeQuery error:", e);

}

return rs;

}

/**

*

* 调用以下的getPrepareStatement(sql)后，可以直接通过以下代码执行sql语句

* preparedStatement.setInt(1, 75);

* preparedStatement.setString(2, "Colombian");

* preparedStatement.executeUpdate();

* @param sql 参数形如：UPDATE COFFEES SET SALES = ? WHERE COF_NAME LIKE ?

* @return

* @throws Exception

*/

public PreparedStatement getPrepareStatement(String sql) throws Exception {

PreparedStatement preparedStatement=conn.prepareStatement(sql);

return preparedStatement;

}

/**

* 更新失败，记得rollBack

* @param sql

* @throws Exception

*/

public void executeUpdate(String sql) throws Exception {

try {

smt.executeUpdate(sql);

conn.commit();

}catch(Exception e) {

if(conn!=null) {

conn.rollback();

log.debug("数据已存在或存在错误，开始回滚。");

}

}

}

public void close() throws Exception {

smt.close();

conn.close();

}

}