nongsanli

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1.    mysql可以对字段进行MD5加密,

　　加密插入：INSERT INTO t_user(id,username,PASSWORD) VALUES('5','pecool',MD5('pecool123'));
　　加密查询：SELECT * FROM t_user WHERE PASSWORD=MD5('pecool123');

　　MD5网传无法解密，因为其算法是单向。

2.分别在oracle、java的jdbc中设置隔离级别

　　2.1 oracle中：https://docs.oracle.com/cloud/latest/db121/LNPLS/static.htm#LNPLS99975    中搜《SET TRANSACTION Statement》

　　　　

DECLARE
  daily_order_total    ,);
  weekly_order_total   ,);
  monthly_order_total  ,);
BEGIN
   COMMIT; -- end previous transaction
   SET TRANSACTION READ ONLY NAME 'Calculate Order Totals';

   SELECT SUM (order_total)
   INTO daily_order_total
   FROM orders
   WHERE order_date = SYSDATE;

   SELECT SUM (order_total)
   INTO weekly_order_total
   FROM orders
   ;

   SELECT SUM (order_total)
   INTO monthly_order_total
   FROM orders
   ;

   COMMIT; -- ends read-only transaction
END;
/

　　2.2jdbc里：Connection类对四种隔离级别进行了常量设置

connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);