oracle数据库操纵语言：DML
添加数据：
(1)直接添加数据：
    insert into table_name(column_name1,column_name2,...) values(data1,data2...);
(2)通过其他数据表添加(目标表已存在)：
    insert into table_name(column_name1,column_name2,...) select column_name1,column_name2... from table_name2;
(3)添加数据同时创建表(目标表待创建)：
    create table table_name as select column_name1,column_name2,...from source_table;
 
修改数据：
    update table_name set column_name1=data1,column_name2=data2,... [where condition];

删除表中数据：
(1)条件删除：
    delete from table_name [where condition];
(2)全部删除：
    truncate table table_name;
    
同时修改和添加：
    merge [into] table_name1
    using table_name2 
    on (condition) 
    when matched then merge_update_clause 
    when not matched then merge_insert_clause;
(1)省略增加的语句
    merge into login 
    using managerinfo 
    on (login.login_id = managerinfo.managerid)
    when matched then update 
    set login.loginname = managerinfo.loginname;
(2)省略修改的语句
    merge into login 
    on(login.login_id=managerinfo.managerid) 
    when not matched then insert 
    values(managerinfo.loginname,managerinfo.password,managerinfo.managerid);
(3)增加和修改同时进行
    merge into login 
    using managerinfo 
    on(login.login_id = managerinfo.managerid)
    when matched then update 
    set login.loginname = managerinfo.loginname 
    when not matched then insert 
    values(managerinfo.loginname,managerinfo.password,managerinfo.managerid);