yhm2046的专栏

jdbc中可以调用函数获取查询语句的列数 ResultSetMetaData rsmd=rest.getMetaData(); int count=rsmd.getColumnCount(); System.out.println("列数为"+count);

#载入sql文件方法: # \. c:\a.sql #3种注释方法:1./**/ 2.# 3.-- 后接空格(oracle语法) /* 创建表: */ /*CREATE TABLE ec_pcuser( -- 自动编号 _pcid int(12) NOT NULL AUTO_INCREMENT PRIMARY KEY, _login varchar(20), _password VARCHAR

#建数据库 #create database db1 #character set 'utf8' #collate 'utf8_general_ci'; #建表 #create table basicRecord ( #no int auto_increment primary key, #name varchar(30) not null, #birthday varchar(30) not

conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=UTF-8","root", "root");

添加外键语法: alter table t_user add constraint u_paid_id2p_id foreign key (u_paid_id) references t_paid (p_id) on delete cascade on update cascade; 注意key后面不要写表名,如果写成这样: alter table t_user add constrain

修改字段:update t_main set name='食品' where m_id='mt001' 增加字段唯一属性:alter table t_main add unique(m_id)