mysql 操作命令小結
| show databases; create database mydb; |
顯示資料庫 建立資料庫 |
| use xxdatabse; | 使用xxdatabse資料庫 |
| show tables; | 顯示某個資料庫下的表格 |
| show create table student; | 顯示student表結構 |
| show tables like "student"; | 顯示資料庫裡是否有student表，若無可以增加建立邏輯 |
| select * from student; | 顯示student表裡的全部學生資訊 |
| drop table student; | 刪除student表 |
| insert into student(field1，field2...) values(?,?,...); | 向student表插入一條資訊，值可以使用佔位符 |
| update student set age=24 where id=3; | 將student表中學號id=3的學生年齡更新為24 |
| delete from student where id=2; | 刪除學生表中id為2的學生資訊 |
| truncate table student; | 清空student表中的全部資訊 |
| create table student(id VARCHAR(10) not NULL,age INYEGER, name VARCHAR(25), primary key(id)); | 建立表student，主鍵為id |
| replace into student(id,name,age) values(1, '小紅', 18); | del+insert結合的原子操作，資料庫存在含主鍵的資訊就更新，否則插入資訊 |
| USE mysql; FLUSH PRIVILEGES; |
在命令視窗執行。解決navicat客戶端建立連結報“client does not support authentication protocol requested...”錯誤 |
| wget http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm rpm -ivh mysql-community-release-el7-5.noarch.rpm sudo yum install mysql-server mysql |
centos安裝mysql |
| use mysql; update user set password=password('new password') where user='root'; flush privileges; |
修改root密碼 |
| mysql -u root -p; use mysql; create user 'test'@'localhost' identified by 'pwd'; flush privileges; grant select privileges on testdb.* to test@localhost identified by '1234'; |
管理員身份登陸 切換資料庫 建立使用者，其中localhost可指定具體IP 重新整理 授權test使用者擁有testdb資料庫下所有表的查詢許可權，連結密碼1234 |
| UPDATE hdfsvcore SET totalCost= (totalCost - LEAST(vcorecost, memcost)); UPDATE hdfsvcore SET totalCost=ROUND(GREATEST(vcorecost, memcost),2); UPDATE director SET dirSize= SUBSTRING(dirSize,1,LENGTH(dirSize)- 3); UPDATE jobinfo SET memory= SUBSTRING(memory,1,LENGTH(memory)- 2) WHERE locate('GS', memory); |
更新資料庫某欄位的值減去另一列的值； 四捨五入，保留2位小數； 字串擷取，將dirSize末尾三個字元截斷，SUBSTRING是從1開始計數，而不是0； 將jobinfo裡memory欄位含有“GS”字元去掉末尾兩字元，locate判斷是否包含某字串； |
| INSERT INTO dirtwo(date, levelDir, dirSize, upDir, nodeServer, ownner) SELECT date, levelDir, dirSize, upDir, nodeServer, ownner FROM dirtwo_copy; | 將一個表的條目插入到另一個表 |
| ALTER TABLE vcorecost ADD vmem FLOAT; ALTER TABLE diruser MODIFY sumSize FLOAT; ALTER TABLE director convert to character set utf8; ALTER TABLE director CHANGE levelDir levelDir VARCHAR(225) CHARACTER SET utf8 NOT NULL; |
增加表字段vmem； 將sumSize改成float型； 修改director表的編碼為utf-8； 將director表的levelDir的字元長度變成225，並設定其編碼為utf-8； |
| SELECT pro.clusterName,pro.userName,pro.productType,pro.dept,jobinfo.cost, jobinfo.type,jobinfo.queueName,jobinfo.vcores,jobinfo.timeConsuming,jobinfo.memory, jobinfo.`level`,jobinfo.resourceWasted FROM (SELECT distinct userName,clusterName, productType, dept FROM cluster_user) as pro INNER JOIN jobinfo ON jobinfo.date='20181009' AND jobinfo.clusterName=pro.clusterName AND jobinfo.ownner=pro.userName; |
級聯查詢。取出興趣資料，先從cluster_user中拿到需要資料重新命名成臨時表pro，再連和jobinfo表做篩選，where條件是兩個表的date和clusterName以及ownner一致； |
| SELECT sum(cost) FROM jobinfo WHERE date='20181010' AND ownner='searchtool'; SELECT COUNT(*) FROM jobinfo WHERE date='20181010'; |
查詢jobinfo表，將符合條件的欄位cost求和 統計20181010這天jobinfo表有多少條目 |