mysql初步学习

1.insert_select 的使用：从一个表复制数据给另一个表

INSERT INTO students(name,sex,LikeBooksNUM,LikesportNUM,average)
SELECT
name,sex,LikeBooksNUM,LikesportNUM,average
FROM students_copy;2.REGEXP :正则表达式的使用，BINARY 是标明正则的检索区分大小写

SELECT students.`name` FROM students WHERE students.`name` REGEXP BINARY "Jack";

3.聚合函数，COUNT（*），AS　表别名，GROUP BY,WITH ROLLUP

SELECT sex ,COUNT(*) AS Sex_num  FROM students GROUP BY sex WITH ROLLUP;

4,左外部联结 LEFT/RIGHT OUTER　JOIN  表列名  ON 联结：选择左边/右边所有的行：例如可以检索某些值为NULL的列

SELECT students.`name`,students.sex,COUNT(sorce.average) AS average_num
FROM students LEFT OUTER JOIN  sorce ON students.average=sorce.average GROUP BY students.name;5，使用触发器：CREATE TRIGGER（触发器）AFTER INSERT ON students_copy 更新的表  FOR EACH ROW UPDATE 执行更新手段 （students_count SET students_count=students_count+1）

CREATE TRIGGER newname AFTER INSERT ON students_copy FOR EACH ROW
UPDATE students_count SET students_count=students_count+1;6，UPDATE 要操作的表 SET 操作指令 WHERE 查询条件：需要注意的是 列名要避开mysql的关键字，例如：name等；

UPDATE students_copy
SET `students_name`="david" WHERE average=100;7，联结表的操作，使操作变得更简单

SELECT
students.`name`
FROM students,sorce,books
WHERE students.average=sorce.average AND sorce.id=books.id AND books.id=161034168，表的自联结：

SELECT s1.name,s1.average FROM students AS s1,students AS s2 WHERE s1.`name`=s2.`name` AND s1.LikeBooksNUM=3;