MySQL學習之一：基礎查詢，排序查詢，條件查詢！！！

時間 2020-08-12 標籤 mysql 學習之一基礎查詢排序條件

MySQL學習之一：基礎查詢，排序查詢，條件查詢！！！

大學學的是sqlserver2008,出來才發現大多用的是MySQL,好在語法都是同樣的，基礎也就是有的。java

先嘮叨兩句，爲何大多用MySQL呀，跨平臺性，開源，部分收費，對於微軟的數據庫，只能運行在windos上，這也就是一個侷限性了，咱們要的是部署在服務器的數據庫，也就是linux上部署數據庫，雖然說微軟也有服務器上運行的系統，但大多仍是在使用linux服務器系統。而MySQL是能夠部署到Linux服務器系統的。mysql

其餘的數據庫還有DB2,甲骨文的數據庫。linux

咱們在本身的電腦上安裝MySQL，至關於c/s架構，服務器端是MySQL。sql

怎麼說呢，安裝本身去MySQL，建議是5.7，感受5.5和5.6版本的安裝費勁，數據庫

對於圖形化我用的是SQLyog操做數據庫。windows

從基礎開始。服務器

##數據庫的好處
    1.持久化數據到本地
    2.能夠實現結構化查詢，方便管理
##數據庫相關概念
    一、DB：數據庫，保存一組有組織的數據的容器
    二、DBMS：數據庫管理系統，又稱爲數據庫軟件（產品），用於管理DB中的數據
    三、SQL:結構化查詢語言，用於和DBMS通訊的語言

##數據庫存儲數據的特色
    一、將數據放到表中，表再放到庫中
    二、一個數據庫中能夠有多個表，每一個表都有一個的名字，用來標識本身。表名具備惟一性。
    三、表具備一些特性，這些特性定義了數據在表中如何存儲，相似java中「類」的設計。
    四、表由列組成，咱們也稱爲字段。全部表都是由一個或多個列組成的，每一列相似java 中的」屬性」
    五、表中的數據是按行存儲的，每一行相似於java中的「對象」。

##MySQL產品的使用
###MySQL服務的啓動和中止
    方式一：計算機——右擊管理——服務
    方式二：經過管理員身份運行
    net start 服務名（啓動服務）
    net stop 服務名（中止服務）

###MySQL服務的登陸和退出
    方式一：經過mysql自帶的客戶端
    只限於root用戶

    方式二：經過windows自帶的客戶端
    登陸：
    mysql 【-h主機名 -P端口號】-u用戶名 -p密碼

    退出：
    exit或ctrl+C

###SQL語言的分類

    一、DQL語言：Data Query Language 數據查詢語言  ★
            select

    二、DML語言：Data Multipulation Language 數據操做語言 ★
            insert、update、delete
    三、DDL語言：Data Define Language 數據定義語言
            create、drop、alter
    四、DCL語言：Data Control Language數據控制語言
            TCL：Transaction Control Language事務控制語言
            commit、rollback

###MySQL語法規範

1.不區分大小寫，建議關鍵字大寫，表名和列名小寫
2.每句命令的結尾使用分號

3.sql中的註釋

    方式一：單行註釋
            -- 註釋文字
    方式二：單行註釋
            #註釋文字
    方式三：多行註釋
            /*註釋文字*/

4.每句命令，根據須要能夠換行，但關鍵字或表名、列名不能夠拆開架構

上代碼：（就是關鍵字，語法，好在sql語言是個弱語言）ide

先從有歧義的開始（在具體的代碼中也會再次提到）函數

DESC 加表名獲取表的結構，包含的字段（也就是列表名）等。

DESC 同時也是降序的關鍵字，這裏不用弄混！！！

java中+的做用

一、加法運算

二、拼接

sql中+的做用

加法運算！！

特色：

①兩個數值型相加，就是普通的加法運算

②若是其中一方爲字符型，則試圖將字符轉換成數值，若是轉換成功，則直接加法運算

若是轉換失敗，則將該字符轉換成0，而後再加法運算

③若是其中一方爲null，則結果確定爲null

千萬不要搞混！！！！！！這也就引出除了，IFNULL的使用。

IFNULL(字段（列名），要替換的值) 當用CONTI 進行拼接時，要拼接的內容中存在null值時，則結果就爲null了，這時候咱們就須要使用IFNULL關鍵字了，若是字段爲NULL，則用要替換的值替換，這裏要注意要替換的值必須和字段規定的數據類型一致。

一）關係表達式

經過關係運算符組成的表達式：關係表達式

java中的判斷相等時用==，而sql中是=

sql中不等因而<>,可是它是支持！=的

sql中的關係運算符：> < >= <= = （!= <>）

二）邏輯表達式

經過邏輯運算符組成的表達式：邏輯不是

sql中的邏輯運算符：and、or 、not 【&& || ！】

必定要和Java中的區分開，

下面就能夠開始基礎的了！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！

例子中用到的數據庫，本身能夠去執行添加一下

/*
SQLyog Ultimate v10.00 Beta1
MySQL - 5.5.15 : Database - myemployees
*********************************************************************
*/


/*!40101 SET NAMES utf8 */;

/*!40101 SET SQL_MODE=''*/;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/`myemployees` /*!40100 DEFAULT CHARACTER SET gb2312 */;

USE `myemployees`;

/*Table structure for table `departments` */

DROP TABLE IF EXISTS `departments`;

CREATE TABLE `departments` (
  `department_id` int(4) NOT NULL AUTO_INCREMENT,
  `department_name` varchar(3) DEFAULT NULL,
  `manager_id` int(6) DEFAULT NULL,
  `location_id` int(4) DEFAULT NULL,
  PRIMARY KEY (`department_id`),
  KEY `loc_id_fk` (`location_id`),
  CONSTRAINT `loc_id_fk` FOREIGN KEY (`location_id`) REFERENCES `locations` (`location_id`)
) ENGINE=InnoDB AUTO_INCREMENT=271 DEFAULT CHARSET=gb2312;

/*Data for the table `departments` */

insert  into `departments`(`department_id`,`department_name`,`manager_id`,`location_id`) values (10,'Adm',200,1700),(20,'Mar',201,1800),(30,'Pur',114,1700),(40,'Hum',203,2400),(50,'Shi',121,1500),(60,'IT',103,1400),(70,'Pub',204,2700),(80,'Sal',145,2500),(90,'Exe',100,1700),(100,'Fin',108,1700),(110,'Acc',205,1700),(120,'Tre',NULL,1700),(130,'Cor',NULL,1700),(140,'Con',NULL,1700),(150,'Sha',NULL,1700),(160,'Ben',NULL,1700),(170,'Man',NULL,1700),(180,'Con',NULL,1700),(190,'Con',NULL,1700),(200,'Ope',NULL,1700),(210,'IT ',NULL,1700),(220,'NOC',NULL,1700),(230,'IT ',NULL,1700),(240,'Gov',NULL,1700),(250,'Ret',NULL,1700),(260,'Rec',NULL,1700),(270,'Pay',NULL,1700);

/*Table structure for table `employees` */

DROP TABLE IF EXISTS `employees`;

CREATE TABLE `employees` (
  `employee_id` int(6) NOT NULL AUTO_INCREMENT,
  `first_name` varchar(20) DEFAULT NULL,
  `last_name` varchar(25) DEFAULT NULL,
  `email` varchar(25) DEFAULT NULL,
  `phone_number` varchar(20) DEFAULT NULL,
  `job_id` varchar(10) DEFAULT NULL,
  `salary` double(10,2) DEFAULT NULL,
  `commission_pct` double(4,2) DEFAULT NULL,
  `manager_id` int(6) DEFAULT NULL,
  `department_id` int(4) DEFAULT NULL,
  `hiredate` datetime DEFAULT NULL,
  PRIMARY KEY (`employee_id`),
  KEY `dept_id_fk` (`department_id`),
  KEY `job_id_fk` (`job_id`),
  CONSTRAINT `dept_id_fk` FOREIGN KEY (`department_id`) REFERENCES `departments` (`department_id`),
  CONSTRAINT `job_id_fk` FOREIGN KEY (`job_id`) REFERENCES `jobs` (`job_id`)
) ENGINE=InnoDB AUTO_INCREMENT=207 DEFAULT CHARSET=gb2312;

/*Data for the table `employees` */

insert  into `employees`(`employee_id`,`first_name`,`last_name`,`email`,`phone_number`,`job_id`,`salary`,`commission_pct`,`manager_id`,`department_id`,`hiredate`) values (100,'Steven','K_ing','SKING','515.123.4567','AD_PRES',24000.00,NULL,NULL,90,'1992-04-03 00:00:00'),(101,'Neena','Kochhar','NKOCHHAR','515.123.4568','AD_VP',17000.00,NULL,100,90,'1992-04-03 00:00:00'),(102,'Lex','De Haan','LDEHAAN','515.123.4569','AD_VP',17000.00,NULL,100,90,'1992-04-03 00:00:00'),(103,'Alexander','Hunold','AHUNOLD','590.423.4567','IT_PROG',9000.00,NULL,102,60,'1992-04-03 00:00:00'),(104,'Bruce','Ernst','BERNST','590.423.4568','IT_PROG',6000.00,NULL,103,60,'1992-04-03 00:00:00'),(105,'David','Austin','DAUSTIN','590.423.4569','IT_PROG',4800.00,NULL,103,60,'1998-03-03 00:00:00'),(106,'Valli','Pataballa','VPATABAL','590.423.4560','IT_PROG',4800.00,NULL,103,60,'1998-03-03 00:00:00'),(107,'Diana','Lorentz','DLORENTZ','590.423.5567','IT_PROG',4200.00,NULL,103,60,'1998-03-03 00:00:00'),(108,'Nancy','Greenberg','NGREENBE','515.124.4569','FI_MGR',12000.00,NULL,101,100,'1998-03-03 00:00:00'),(109,'Daniel','Faviet','DFAVIET','515.124.4169','FI_ACCOUNT',9000.00,NULL,108,100,'1998-03-03 00:00:00'),(110,'John','Chen','JCHEN','515.124.4269','FI_ACCOUNT',8200.00,NULL,108,100,'2000-09-09 00:00:00'),(111,'Ismael','Sciarra','ISCIARRA','515.124.4369','FI_ACCOUNT',7700.00,NULL,108,100,'2000-09-09 00:00:00'),(112,'Jose Manuel','Urman','JMURMAN','515.124.4469','FI_ACCOUNT',7800.00,NULL,108,100,'2000-09-09 00:00:00'),(113,'Luis','Popp','LPOPP','515.124.4567','FI_ACCOUNT',6900.00,NULL,108,100,'2000-09-09 00:00:00'),(114,'Den','Raphaely','DRAPHEAL','515.127.4561','PU_MAN',11000.00,NULL,100,30,'2000-09-09 00:00:00'),(115,'Alexander','Khoo','AKHOO','515.127.4562','PU_CLERK',3100.00,NULL,114,30,'2000-09-09 00:00:00'),(116,'Shelli','Baida','SBAIDA','515.127.4563','PU_CLERK',2900.00,NULL,114,30,'2000-09-09 00:00:00'),(117,'Sigal','Tobias','STOBIAS','515.127.4564','PU_CLERK',2800.00,NULL,114,30,'2000-09-09 00:00:00'),(118,'Guy','Himuro','GHIMURO','515.127.4565','PU_CLERK',2600.00,NULL,114,30,'2000-09-09 00:00:00'),(119,'Karen','Colmenares','KCOLMENA','515.127.4566','PU_CLERK',2500.00,NULL,114,30,'2000-09-09 00:00:00'),(120,'Matthew','Weiss','MWEISS','650.123.1234','ST_MAN',8000.00,NULL,100,50,'2004-02-06 00:00:00'),(121,'Adam','Fripp','AFRIPP','650.123.2234','ST_MAN',8200.00,NULL,100,50,'2004-02-06 00:00:00'),(122,'Payam','Kaufling','PKAUFLIN','650.123.3234','ST_MAN',7900.00,NULL,100,50,'2004-02-06 00:00:00'),(123,'Shanta','Vollman','SVOLLMAN','650.123.4234','ST_MAN',6500.00,NULL,100,50,'2004-02-06 00:00:00'),(124,'Kevin','Mourgos','KMOURGOS','650.123.5234','ST_MAN',5800.00,NULL,100,50,'2004-02-06 00:00:00'),(125,'Julia','Nayer','JNAYER','650.124.1214','ST_CLERK',3200.00,NULL,120,50,'2004-02-06 00:00:00'),(126,'Irene','Mikkilineni','IMIKKILI','650.124.1224','ST_CLERK',2700.00,NULL,120,50,'2004-02-06 00:00:00'),(127,'James','Landry','JLANDRY','650.124.1334','ST_CLERK',2400.00,NULL,120,50,'2004-02-06 00:00:00'),(128,'Steven','Markle','SMARKLE','650.124.1434','ST_CLERK',2200.00,NULL,120,50,'2004-02-06 00:00:00'),(129,'Laura','Bissot','LBISSOT','650.124.5234','ST_CLERK',3300.00,NULL,121,50,'2004-02-06 00:00:00'),(130,'Mozhe','Atkinson','MATKINSO','650.124.6234','ST_CLERK',2800.00,NULL,121,50,'2004-02-06 00:00:00'),(131,'James','Marlow','JAMRLOW','650.124.7234','ST_CLERK',2500.00,NULL,121,50,'2004-02-06 00:00:00'),(132,'TJ','Olson','TJOLSON','650.124.8234','ST_CLERK',2100.00,NULL,121,50,'2004-02-06 00:00:00'),(133,'Jason','Mallin','JMALLIN','650.127.1934','ST_CLERK',3300.00,NULL,122,50,'2004-02-06 00:00:00'),(134,'Michael','Rogers','MROGERS','650.127.1834','ST_CLERK',2900.00,NULL,122,50,'2002-12-23 00:00:00'),(135,'Ki','Gee','KGEE','650.127.1734','ST_CLERK',2400.00,NULL,122,50,'2002-12-23 00:00:00'),(136,'Hazel','Philtanker','HPHILTAN','650.127.1634','ST_CLERK',2200.00,NULL,122,50,'2002-12-23 00:00:00'),(137,'Renske','Ladwig','RLADWIG','650.121.1234','ST_CLERK',3600.00,NULL,123,50,'2002-12-23 00:00:00'),(138,'Stephen','Stiles','SSTILES','650.121.2034','ST_CLERK',3200.00,NULL,123,50,'2002-12-23 00:00:00'),(139,'John','Seo','JSEO','650.121.2019','ST_CLERK',2700.00,NULL,123,50,'2002-12-23 00:00:00'),(140,'Joshua','Patel','JPATEL','650.121.1834','ST_CLERK',2500.00,NULL,123,50,'2002-12-23 00:00:00'),(141,'Trenna','Rajs','TRAJS','650.121.8009','ST_CLERK',3500.00,NULL,124,50,'2002-12-23 00:00:00'),(142,'Curtis','Davies','CDAVIES','650.121.2994','ST_CLERK',3100.00,NULL,124,50,'2002-12-23 00:00:00'),(143,'Randall','Matos','RMATOS','650.121.2874','ST_CLERK',2600.00,NULL,124,50,'2002-12-23 00:00:00'),(144,'Peter','Vargas','PVARGAS','650.121.2004','ST_CLERK',2500.00,NULL,124,50,'2002-12-23 00:00:00'),(145,'John','Russell','JRUSSEL','011.44.1344.429268','SA_MAN',14000.00,0.40,100,80,'2002-12-23 00:00:00'),(146,'Karen','Partners','KPARTNER','011.44.1344.467268','SA_MAN',13500.00,0.30,100,80,'2002-12-23 00:00:00'),(147,'Alberto','Errazuriz','AERRAZUR','011.44.1344.429278','SA_MAN',12000.00,0.30,100,80,'2002-12-23 00:00:00'),(148,'Gerald','Cambrault','GCAMBRAU','011.44.1344.619268','SA_MAN',11000.00,0.30,100,80,'2002-12-23 00:00:00'),(149,'Eleni','Zlotkey','EZLOTKEY','011.44.1344.429018','SA_MAN',10500.00,0.20,100,80,'2002-12-23 00:00:00'),(150,'Peter','Tucker','PTUCKER','011.44.1344.129268','SA_REP',10000.00,0.30,145,80,'2014-03-05 00:00:00'),(151,'David','Bernstein','DBERNSTE','011.44.1344.345268','SA_REP',9500.00,0.25,145,80,'2014-03-05 00:00:00'),(152,'Peter','Hall','PHALL','011.44.1344.478968','SA_REP',9000.00,0.25,145,80,'2014-03-05 00:00:00'),(153,'Christopher','Olsen','COLSEN','011.44.1344.498718','SA_REP',8000.00,0.20,145,80,'2014-03-05 00:00:00'),(154,'Nanette','Cambrault','NCAMBRAU','011.44.1344.987668','SA_REP',7500.00,0.20,145,80,'2014-03-05 00:00:00'),(155,'Oliver','Tuvault','OTUVAULT','011.44.1344.486508','SA_REP',7000.00,0.15,145,80,'2014-03-05 00:00:00'),(156,'Janette','K_ing','JKING','011.44.1345.429268','SA_REP',10000.00,0.35,146,80,'2014-03-05 00:00:00'),(157,'Patrick','Sully','PSULLY','011.44.1345.929268','SA_REP',9500.00,0.35,146,80,'2014-03-05 00:00:00'),(158,'Allan','McEwen','AMCEWEN','011.44.1345.829268','SA_REP',9000.00,0.35,146,80,'2014-03-05 00:00:00'),(159,'Lindsey','Smith','LSMITH','011.44.1345.729268','SA_REP',8000.00,0.30,146,80,'2014-03-05 00:00:00'),(160,'Louise','Doran','LDORAN','011.44.1345.629268','SA_REP',7500.00,0.30,146,80,'2014-03-05 00:00:00'),(161,'Sarath','Sewall','SSEWALL','011.44.1345.529268','SA_REP',7000.00,0.25,146,80,'2014-03-05 00:00:00'),(162,'Clara','Vishney','CVISHNEY','011.44.1346.129268','SA_REP',10500.00,0.25,147,80,'2014-03-05 00:00:00'),(163,'Danielle','Greene','DGREENE','011.44.1346.229268','SA_REP',9500.00,0.15,147,80,'2014-03-05 00:00:00'),(164,'Mattea','Marvins','MMARVINS','011.44.1346.329268','SA_REP',7200.00,0.10,147,80,'2014-03-05 00:00:00'),(165,'David','Lee','DLEE','011.44.1346.529268','SA_REP',6800.00,0.10,147,80,'2014-03-05 00:00:00'),(166,'Sundar','Ande','SANDE','011.44.1346.629268','SA_REP',6400.00,0.10,147,80,'2014-03-05 00:00:00'),(167,'Amit','Banda','ABANDA','011.44.1346.729268','SA_REP',6200.00,0.10,147,80,'2014-03-05 00:00:00'),(168,'Lisa','Ozer','LOZER','011.44.1343.929268','SA_REP',11500.00,0.25,148,80,'2014-03-05 00:00:00'),(169,'Harrison','Bloom','HBLOOM','011.44.1343.829268','SA_REP',10000.00,0.20,148,80,'2014-03-05 00:00:00'),(170,'Tayler','Fox','TFOX','011.44.1343.729268','SA_REP',9600.00,0.20,148,80,'2014-03-05 00:00:00'),(171,'William','Smith','WSMITH','011.44.1343.629268','SA_REP',7400.00,0.15,148,80,'2014-03-05 00:00:00'),(172,'Elizabeth','Bates','EBATES','011.44.1343.529268','SA_REP',7300.00,0.15,148,80,'2014-03-05 00:00:00'),(173,'Sundita','Kumar','SKUMAR','011.44.1343.329268','SA_REP',6100.00,0.10,148,80,'2014-03-05 00:00:00'),(174,'Ellen','Abel','EABEL','011.44.1644.429267','SA_REP',11000.00,0.30,149,80,'2014-03-05 00:00:00'),(175,'Alyssa','Hutton','AHUTTON','011.44.1644.429266','SA_REP',8800.00,0.25,149,80,'2014-03-05 00:00:00'),(176,'Jonathon','Taylor','JTAYLOR','011.44.1644.429265','SA_REP',8600.00,0.20,149,80,'2014-03-05 00:00:00'),(177,'Jack','Livingston','JLIVINGS','011.44.1644.429264','SA_REP',8400.00,0.20,149,80,'2014-03-05 00:00:00'),(178,'Kimberely','Grant','KGRANT','011.44.1644.429263','SA_REP',7000.00,0.15,149,NULL,'2014-03-05 00:00:00'),(179,'Charles','Johnson','CJOHNSON','011.44.1644.429262','SA_REP',6200.00,0.10,149,80,'2014-03-05 00:00:00'),(180,'Winston','Taylor','WTAYLOR','650.507.9876','SH_CLERK',3200.00,NULL,120,50,'2014-03-05 00:00:00'),(181,'Jean','Fleaur','JFLEAUR','650.507.9877','SH_CLERK',3100.00,NULL,120,50,'2014-03-05 00:00:00'),(182,'Martha','Sullivan','MSULLIVA','650.507.9878','SH_CLERK',2500.00,NULL,120,50,'2014-03-05 00:00:00'),(183,'Girard','Geoni','GGEONI','650.507.9879','SH_CLERK',2800.00,NULL,120,50,'2014-03-05 00:00:00'),(184,'Nandita','Sarchand','NSARCHAN','650.509.1876','SH_CLERK',4200.00,NULL,121,50,'2014-03-05 00:00:00'),(185,'Alexis','Bull','ABULL','650.509.2876','SH_CLERK',4100.00,NULL,121,50,'2014-03-05 00:00:00'),(186,'Julia','Dellinger','JDELLING','650.509.3876','SH_CLERK',3400.00,NULL,121,50,'2014-03-05 00:00:00'),(187,'Anthony','Cabrio','ACABRIO','650.509.4876','SH_CLERK',3000.00,NULL,121,50,'2014-03-05 00:00:00'),(188,'Kelly','Chung','KCHUNG','650.505.1876','SH_CLERK',3800.00,NULL,122,50,'2014-03-05 00:00:00'),(189,'Jennifer','Dilly','JDILLY','650.505.2876','SH_CLERK',3600.00,NULL,122,50,'2014-03-05 00:00:00'),(190,'Timothy','Gates','TGATES','650.505.3876','SH_CLERK',2900.00,NULL,122,50,'2014-03-05 00:00:00'),(191,'Randall','Perkins','RPERKINS','650.505.4876','SH_CLERK',2500.00,NULL,122,50,'2014-03-05 00:00:00'),(192,'Sarah','Bell','SBELL','650.501.1876','SH_CLERK',4000.00,NULL,123,50,'2014-03-05 00:00:00'),(193,'Britney','Everett','BEVERETT','650.501.2876','SH_CLERK',3900.00,NULL,123,50,'2014-03-05 00:00:00'),(194,'Samuel','McCain','SMCCAIN','650.501.3876','SH_CLERK',3200.00,NULL,123,50,'2014-03-05 00:00:00'),(195,'Vance','Jones','VJONES','650.501.4876','SH_CLERK',2800.00,NULL,123,50,'2014-03-05 00:00:00'),(196,'Alana','Walsh','AWALSH','650.507.9811','SH_CLERK',3100.00,NULL,124,50,'2014-03-05 00:00:00'),(197,'Kevin','Feeney','KFEENEY','650.507.9822','SH_CLERK',3000.00,NULL,124,50,'2014-03-05 00:00:00'),(198,'Donald','OConnell','DOCONNEL','650.507.9833','SH_CLERK',2600.00,NULL,124,50,'2014-03-05 00:00:00'),(199,'Douglas','Grant','DGRANT','650.507.9844','SH_CLERK',2600.00,NULL,124,50,'2014-03-05 00:00:00'),(200,'Jennifer','Whalen','JWHALEN','515.123.4444','AD_ASST',4400.00,NULL,101,10,'2016-03-03 00:00:00'),(201,'Michael','Hartstein','MHARTSTE','515.123.5555','MK_MAN',13000.00,NULL,100,20,'2016-03-03 00:00:00'),(202,'Pat','Fay','PFAY','603.123.6666','MK_REP',6000.00,NULL,201,20,'2016-03-03 00:00:00'),(203,'Susan','Mavris','SMAVRIS','515.123.7777','HR_REP',6500.00,NULL,101,40,'2016-03-03 00:00:00'),(204,'Hermann','Baer','HBAER','515.123.8888','PR_REP',10000.00,NULL,101,70,'2016-03-03 00:00:00'),(205,'Shelley','Higgins','SHIGGINS','515.123.8080','AC_MGR',12000.00,NULL,101,110,'2016-03-03 00:00:00'),(206,'William','Gietz','WGIETZ','515.123.8181','AC_ACCOUNT',8300.00,NULL,205,110,'2016-03-03 00:00:00');

/*Table structure for table `jobs` */

DROP TABLE IF EXISTS `jobs`;

CREATE TABLE `jobs` (
  `job_id` varchar(10) NOT NULL,
  `job_title` varchar(35) DEFAULT NULL,
  `min_salary` int(6) DEFAULT NULL,
  `max_salary` int(6) DEFAULT NULL,
  PRIMARY KEY (`job_id`)
) ENGINE=InnoDB DEFAULT CHARSET=gb2312;

/*Data for the table `jobs` */

insert  into `jobs`(`job_id`,`job_title`,`min_salary`,`max_salary`) values ('AC_ACCOUNT','Public Accountant',4200,9000),('AC_MGR','Accounting Manager',8200,16000),('AD_ASST','Administration Assistant',3000,6000),('AD_PRES','President',20000,40000),('AD_VP','Administration Vice President',15000,30000),('FI_ACCOUNT','Accountant',4200,9000),('FI_MGR','Finance Manager',8200,16000),('HR_REP','Human Resources Representative',4000,9000),('IT_PROG','Programmer',4000,10000),('MK_MAN','Marketing Manager',9000,15000),('MK_REP','Marketing Representative',4000,9000),('PR_REP','Public Relations Representative',4500,10500),('PU_CLERK','Purchasing Clerk',2500,5500),('PU_MAN','Purchasing Manager',8000,15000),('SA_MAN','Sales Manager',10000,20000),('SA_REP','Sales Representative',6000,12000),('SH_CLERK','Shipping Clerk',2500,5500),('ST_CLERK','Stock Clerk',2000,5000),('ST_MAN','Stock Manager',5500,8500);

/*Table structure for table `locations` */

DROP TABLE IF EXISTS `locations`;

CREATE TABLE `locations` (
  `location_id` int(11) NOT NULL AUTO_INCREMENT,
  `street_address` varchar(40) DEFAULT NULL,
  `postal_code` varchar(12) DEFAULT NULL,
  `city` varchar(30) DEFAULT NULL,
  `state_province` varchar(25) DEFAULT NULL,
  `country_id` varchar(2) DEFAULT NULL,
  PRIMARY KEY (`location_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3201 DEFAULT CHARSET=gb2312;

/*Data for the table `locations` */

insert  into `locations`(`location_id`,`street_address`,`postal_code`,`city`,`state_province`,`country_id`) values (1000,'1297 Via Cola di Rie','00989','Roma',NULL,'IT'),(1100,'93091 Calle della Testa','10934','Venice',NULL,'IT'),(1200,'2017 Shinjuku-ku','1689','Tokyo','Tokyo Prefecture','JP'),(1300,'9450 Kamiya-cho','6823','Hiroshima',NULL,'JP'),(1400,'2014 Jabberwocky Rd','26192','Southlake','Texas','US'),(1500,'2011 Interiors Blvd','99236','South San Francisco','California','US'),(1600,'2007 Zagora St','50090','South Brunswick','New Jersey','US'),(1700,'2004 Charade Rd','98199','Seattle','Washington','US'),(1800,'147 Spadina Ave','M5V 2L7','Toronto','Ontario','CA'),(1900,'6092 Boxwood St','YSW 9T2','Whitehorse','Yukon','CA'),(2000,'40-5-12 Laogianggen','190518','Beijing',NULL,'CN'),(2100,'1298 Vileparle (E)','490231','Bombay','Maharashtra','IN'),(2200,'12-98 Victoria Street','2901','Sydney','New South Wales','AU'),(2300,'198 Clementi North','540198','Singapore',NULL,'SG'),(2400,'8204 Arthur St',NULL,'London',NULL,'UK'),(2500,'Magdalen Centre, The Oxford Science Park','OX9 9ZB','Oxford','Oxford','UK'),(2600,'9702 Chester Road','09629850293','Stretford','Manchester','UK'),(2700,'Schwanthalerstr. 7031','80925','Munich','Bavaria','DE'),(2800,'Rua Frei Caneca 1360 ','01307-002','Sao Paulo','Sao Paulo','BR'),(2900,'20 Rue des Corps-Saints','1730','Geneva','Geneve','CH'),(3000,'Murtenstrasse 921','3095','Bern','BE','CH'),(3100,'Pieter Breughelstraat 837','3029SK','Utrecht','Utrecht','NL'),(3200,'Mariano Escobedo 9991','11932','Mexico City','Distrito Federal,','MX');

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

常見的：

#顯示該鏈接下全部的庫

SHOW DATABASES;

#切換到指定的庫

USE test;

#顯示當前庫中的全部表

SHOW TABLES ;

#顯示指定庫中的全部表

SHOW TABLES FROM mysql;

#查看指定表的結構

DESC student;

#查看當前服務器的版本

SELECT VERSION()

#進階1：基礎查詢

語法：

select 查詢列表 from 表名;

特色：

1.查詢的結果爲一個虛擬表，並無真實存在

2.查詢列表能夠是常量、字段、表達式、函數以及上述的組合

相似於 System.out.println("");

補充函數：

concat拼接

version查看版本

database查看當前打開的數據庫

user查看當前的用戶

ifnull判斷某字段或表達式是否爲null，若是爲null則顯示指定的值

*/

USE  myemployees;

#1.查詢常量

/*

若是是數值型的常量，則不用引號

若是是字符型或日期型的常量，最好使用引號

*/

SELECT 'john';

SELECT 100;

#2.查詢表達式

SELECT 100+99;

#3.查詢函數(方法)

SELECT VERSION();-- 查看當前數據庫服務的版本

SELECT DATABASE();-- 查看當前鏈接的數據庫

#4.查詢單個字段

SELECT last_name FROM employees ;

#5.查詢多個字段

SELECT last_name,salary ,first_name FROM employees;

#6.查詢全部字段

#方式一：

#方式二：使用 *

SELECT * FROM employees;

#【綜合案例】查詢函數、字段、常量

SELECT USER(),last_name,salary*12 FROM employees；

#7.起別名

/*

別名值可使用單引號或雙引號引發來，也能夠不引

若是別名值有特殊符號，則必須用引號引發來！

*/

#方式一：使用as

SELECT USER() AS '當前用戶' ;

SELECT

    `employee_id`,

    `first_name`,

    `last_name`,

    `email`,

    `phone_number`,

    `job_id`,

    `salary`,

    `commission_pct`,

    `manager_id`,

    `department_id`,

    `hiredate`

FROM

    employees ;

#方式二：使用空格

SELECT USER() 當前用戶;

#8.+鏈接符

回顧：

java中+的做用

一、加法運算

二、拼接

sql中+的做用

加法運算！！

特色：

①兩個數值型相加，就是普通的加法運算

②若是其中一方爲字符型，則試圖將字符轉換成數值，若是轉換成功，則直接加法運算

若是轉換失敗，則將該字符轉換成0，而後再加法運算

③若是其中一方爲null，則結果確定爲null

select 100+23;      結果 123

select 1.5+2;        結果3.5

select 'john'+100;   結果100

select '234'+100;  結果100

select null+null;   結果null

要知道當鏈接是，一但鏈接的元素中有null的，則結果則爲null(通常對於+ 和concat).

SELECT first_name+last_name FROM employees;

SELECT CONCAT(first_name,last_name) AS 姓名 FROM employees;

#進階2：條件查詢

語法：

select 查詢列表 from 表名

where 條件;

條件的形式：

一）關係表達式

經過關係運算符組成的表達式：關係表達式

sql中的關係運算符：> < >= <= = != <>

二）邏輯表達式

經過邏輯運算符組成的表達式：邏輯不是

sql中的邏輯運算符：and、or 、not 【&& || ！】

三）模糊查詢

like、between and、in、is null

SELECT last_name,first_name,salary,email,department_id,job_id FROM employees;

#1、按關係表達式查詢

#案例1：查詢工資>10000的員工信息

SELECT * FROM employees WHERE salary>10000;

#案例2：查詢 job_id不是'IT_PROG'的員工姓名、job_id、salary

SELECT last_name,job_id,salary

FROM employees

WHERE job_id<>'IT_PROG';

SELECT last_name,job_id,salary

FROM employees

WHERE NOT(job_id='IT_PROG');

#2、按邏輯表達式查詢

#案例1：查詢工資>10000而且小於20000的員工姓名、工資、年薪

SELECT last_name,salary,salary*12*(1+IFNULL(commission_pct,0)) AS 年薪 FROM employees

WHERE salary>10000 AND salary<20000;

#案例2：查詢部門編號不在90到120之間的而且工資>15000的員工信息

SELECT * FROM employees

WHERE NOT(department_id >=90 AND department_id<=120) AND salary>15000;

#3、模糊查詢

#一、like

/*

like通常搭配通配符使用。

常見的通配符：

%：任意0個或多個字符

_：任意單個字符

*/

#案例1：查詢員工信息表中姓名第一個字符爲e的員工信息

SELECT * FROM employees

WHERE last_name LIKE 'e%';

#案例2：查詢員工信息表中姓名第二個字符爲e，第五個字符爲a的員工信息

SELECT * FROM employees

WHERE last_name LIKE '_e__a%';

#案例3：查詢姓名中前面字符爲ernst的員工信息

SELECT * FROM employees

WHERE last_name LIKE 'ernst%';

#方式一：直接經過\進行轉義

**SELECT * FROM employees**

WHERE last_name LIKE '_\_%';

#方式二：經過escape關鍵字指定轉義字符

**SELECT * FROM employees**

WHERE last_name LIKE '_$_%' ESCAPE '$';

#二、between and

/*

特色：

①用於篩選某個字段或表達式是否在指定的區間範圍

②等價於使用邏輯表達式的效果，只是語法上更加簡單

③兩個區間值不能調換順序

④兩個區間值包含

>=左區間 and <=右區間

*/

#案例1：查詢年薪在100000到200000的員工年薪和姓名

SELECT salary*12*(1+IFNULL(commission_pct,0)) 年薪,last_name 姓名

FROM employees

WHERE salary*12*(1+IFNULL(commission_pct,0)) BETWEEN 100000 AND 200000;

#案例2：查詢年薪不在100740到187200的員工年薪和姓名

SELECT salary*12*(1+IFNULL(commission_pct,0)) 年薪,last_name 姓名

FROM employees

WHERE salary*12*(1+IFNULL(commission_pct,0)) NOT BETWEEN 100740 AND 187200

#三、in

說明：在...裏面

特色：

①效果等價於使用or鏈接，只是語法上更加的簡潔

#案例1：查詢工種編號是IT_PROT或是ST_CLERK或是AD_VP的員工信息

#傳統方式：

SELECT * FROM employees

WHERE job_id ='IT_PROG'

OR job_id = 'ST_CLERK'

OR job_id = 'AD_VP';

#in方式

SELECT * FROM employees

WHERE job_id NOT IN('IT_PROG','ST_CLERK','AD_VP');

#四、is null

#案例1：查詢哪一個員工沒有獎金

SELECT * FROM employees

WHERE commission_pct IS NULL;

#案例2：查詢哪一個員工有獎金

SELECT * FROM employees

WHERE commission_pct IS NOT NULL;

#進階3：排序查詢

/*

語法：

select 查詢列表

from 表名

where 條件

order by 排序列表 asc|desc;

特色：

一、asc表明升序，desc表明降序。默認是升序

二、查詢列表能夠是單個字段、多個字段、函數、表達式、別名或上述的組合

*/
#1.按單個字段進行升序 ★

#案例1：按工資從低到高排序

SELECT *

FROM employees

ORDER BY salary ;

#案例2：按工資從低到高排序

SELECT *

FROM employees

ORDER BY salary DESC;

#2.按多個字段排序

#案例1：部門編號>50的按工資從高到低排序，若是同樣，再按frist_name升序

SELECT *

FROM employees

WHERE department_id>50

ORDER BY salary DESC,first_name ASC;

#3.按表達式排序

#案例：將姓名中包含e字符的年薪和姓名顯示出來，而且按年薪進行降序

SELECT salary*12*(1+IFNULL(commission_pct,0)) 年薪,last_name

FROM employees

WHERE last_name LIKE '%e%'

ORDER BY salary*12*(1+IFNULL(commission_pct,0)) DESC;

#4.按別名排序

#案例：將姓名中包含e字符的年薪和姓名顯示出來，而且按年薪進行降序

SELECT salary*12*(1+IFNULL(commission_pct,0)) 年薪,last_name

FROM employees

WHERE last_name LIKE '%e%'

ORDER BY 年薪 DESC;

#5.按函數排序

#案例：顯示全部有獎金的員工姓名、獎金、姓名的長度，按姓名的長度從低到高排序

SELECT last_name,commission_pct ,LENGTH(last_name) 長度

FROM employees

WHERE commission_pct IS NOT NULL

ORDER BY LENGTH(last_name)

MySQL學習之一：基礎查詢，排序查詢，條件查詢！！！