sql數(shù)據(jù)庫基本語句

1、123456789 STUcreate table STU(SNO varchar(7) primary key,SNAME varchar(8),SCLASS 123456789 STUcreate table STU(SNO varchar(7) primary key,SNAME varchar(8),SCLASS AD添加列alter table STU add alter table STU add SSEX L(專業(yè))table L.SPENAME from L SQL查詢語1.2.查詢學SNO,SNAME from distinct用于除去重復為19select * frm ST

2、U where where 可用于輸入查詢的條件限制,SQL關系運算符有4.查為18的男學生學號select SNO,SNAME from STU where SSEX=男 and -and,or,not是SQL的邏輯運算5.查在1820select * from STUand,or,not是SQL的邏輯運算5.查在1820select * from STU where SAGE=18 select * from STU where SAGE bet an表范圍,對應的否定為18 and 20; 查詢專業(yè)為01,02select * from STU where SPENO=01 or 6.1

3、select* from STU where SPENO in01,02); in 表示查詢的集合,否定使用 not in7.查詢所有姓陳的學生信select *from STU where SNAME like陳%; ps:名字中帶有陳應該寫為: SNAME like %陳%字符匹配:%匹配任意個任意字符,_8.select * frm STU is null 代表空,where SPENOisnull; in null 代表不空9.查詢所有學生的學號,使用外鍵,外鍵就是一個的主鍵是另一個表的字段select L.SPENAME from Lwhere 10.查詢計算機專業(yè)的學生學號,名 w

4、here (select SPENO from L where SPENAME=計算機嵌套的查詢從里到外,11.select SPENO,count(*) from STU group by L where group by 12.查詢成績平均 select avg(SGRADE),sum(SGRADE),max(SGRADE) ,inSGAD)fom avg(SGRADE)sum(SGRADE) max(SGRADE) SQL集函數(shù)|count(distinct|all字段名|avg(distinct|all字段名|sum(distinct|all字段名|- 語grant 權限on 表明to 用戶名with grant revoke 權限on 表名from 用戶名列1.有with grant option時 pri