【1】建立員工檔案表　　要求欄位：員工員工編號，員工姓名，性別，工資，email，入職時間，部門。　　【2】合理選擇資料型別及欄位修飾符，要求有NOT NULL，auto_increment, primary key等。　　[sql] view plain copy　　--　　-- make by kakane　　--　　DROP TABLE IF EXISTS `workers_info`;　　CREATE TABLE `workers_info` (　　`id` int(11) NOT NULL AUTO_INCREMENT,　　`workername` varchar(20) NOT NULL,　　`sex` enum(F,M,S),　　`salary` int(11) DEFAULT "0",　　`email` varchar(30),　　`EmployedDates` date,　　`department` varchar(30),　　PRIMARY KEY (`id`)　　) ENGINE=MyISAM DEFAULT CHARSET=utf8;　　mysql> alter table workers_info ADD sex enum("F","M","S");[sql] view plain copy　　【3】查看錶的結構　　[html] view plain copy　　mysql> desc workers_info;　　【4】新增qq和tel欄位，要求tel欄位位於email前，要求入職時間是最後一個欄位mysql> ALTER TABLE workers_info ADD tel varchar(15) after salary;[sql] view plain copy　　mysql> ALTER TABLE workers_info ADD qq int;ALTER TABLE workers_info MODIFY EmployedDates date after qq;【5】把email欄位修改成mailbox　　mysql> ALTER TABLE workers_info CHANGE email mailbox varchar(30);【6】向表裡新增10條記錄　　mysql> INSERT INTO workers_info values(NULL,"xing",10000,"1598232123","[email protected]","yanfa",736019646,20121221);[sql] view plain copy　　mysql> INSERT INTO workers_info (workername,salary,tel,mailbox,department,qq,EmployedDates) values("xing",10000,"1598232123","[email protected]","yanfa",736019646,20121221);【7】修改其中兩條記錄的tel和mailbox　　mysql> UPDATE workers_info SET mailbox = "[email protected]" WHERE id = 14;[sql] view plain copy　　mysql> UPDATE workers_info SET mailbox = "[email protected]",tel="1246543423" WHERE id = 13;【8】檢視所新增記錄　　mysql> select * from workers_info;　　【9】檢視姓名和入職時間記錄　　mysql> select workername,EmployedDates from workers_info;【10】查詢入職時間在2003年以前的　　[sql] view plain copy　　mysql> select * from workers_info where year(EmployedDates) < 2003;[sql] view plain copy　　【11】查詢工資最高和最低的員工姓名　　[sql] view plain copy　　mysql> select * from workers_info ORDER BY salary limit 1;mysql> select * from workers_info ORDER BY salary desc limit 1;【12】查詢平均工資　　[sql] view plain copy　　mysql> select avg(salary) from workers_info;[sql] view plain copy　　【13】統計男員工人數、女員工人數　　[sql] view plain copy　　mysql> select count(男) from workers_info where sex="M";mysql> select count(男) from workers_info where sex="M";【14】按照入職時間先後進行排序，並顯示前5位員工姓名[sql] view plain copy　　mysql> select * from workers_info ORDER BY EmployedDates limit 5;