mysql(3)select简单的查询语句

1)查看查询数据显示

SELECT  *  FORM student;

SELECE  sname 姓名,sscore 分数 FROM student; /*只显示姓名,分数*/

SELECT * FROM student  WHERE  sscore<80;/*查询的基本条件> <  <=  >=  != <> */

SELECT * FROM student WHERE sscore!=82 ;

SELECT *  FROM student WHERE NOT sscore=82;

SELECT * FROM  student WHERE sscore BETWEEN 70 AND 80;/*查询条件between and范围,可以在数字和日期类型划分*/

SELECT * FROM  student  WHERE sbirthday  BETWEEN '1991-1-1' AND '2002-1-1';

-----基本条件like条件%

-----查询姓名是两个字学生信息

SELECT * FROM student WHERE sanem LIKE '__';/*_代表一个任意字符*/

SELECT * FROM student WHERE sname LIKE '%丽%'; /*%代表0个或多个任意字符*/

----基本条件in在某范围内,not in

SELECT  *  FROM  student  WHERE sno   IN (201437,201445,201421)

SELECT * FROM student WHERE  sname=' ';/*查询名字为空的学生信息*/

---基本条件null运算

SELECT * FROM student WHERE sscore  IS NULL;

UPDATE  student  SET sscore=0 WHERE sscore IS NULL;/*将没有成绩的学生成绩改为0分*/