1、資料型別

char 字元 定長，char(10) varchar 字串 int 整數 float 單精度 double 雙精度 date 日期 年月日 timestamp 年月日 時分秒 時間戳

decimal 通常和費用金錢相關的使用該型別

2、設定使用者許可權以及客戶端的IP

grant all privileges on *.* to 'root'@'%' identified by '123456'; flush priviliges;

3、檢視databases以及建立database、切換database

show databases; create database ruozedata;

4、SQL操作型別介紹

DML:insert update delete select 增刪改查 DDL:create database/drop database

5、建立表

每張表基本都需要：建立時間、建立者、修改時間、修改者

create table ruozet1(
id int auto_incremen primary key,

name varchar(100),
age int,
address varchar(100),

create_time timestamp default current_timestamp,
create_user varchar(100),
update_time timestamp default current_timestamp on update current_timestamp,
update_user varchar(100)
)ENGING=InnoDB default CHARSET=utf-8;
 

– id主鍵自增長，唯一 – default current_timestamp建立時預設時間 – default current_timestamp on update current_timestamp 新增時以及更新時都會寫入當前時間

insert into ruozedata (name,age) values ('張三',18);

6、增刪改查資料

新增資料 insert into ruozedata(id, name, age) values(1,‘zhangsan’,18); 修改資料指定id的資訊(高危，請檢查好where) update ruozedata set age=20,address=‘北京’ where id = 1; 刪除指定id的資料 delete from ruozedata where id = 1; 清空表(高危，請再三確認where條件，必要時可以先做備份) delete from ruozedata; 查詢資料 select id,name,age from ruozedata;

7、例子

以下表全部來自於Oracle官方例子

--部門表
dept部門表(deptno部門編號/dname部門名稱/loc地點)

create table dept (
    deptno numeric(2),
    dname varchar(14),
    loc varchar(13)
);

insert into dept values (10, 'ACCOUNTING', 'NEW YORK');
insert into dept values (20, 'RESEARCH', 'DALLAS');
insert into dept values (30, 'SALES', 'CHICAGO');
insert into dept values (40, 'OPERATIONS', 'BOSTON');

--工資等級表
salgrade工資等級表(grade 等級/losal此等級的最低/hisal此等級的最高)
create table salgrade (
    grade numeric,
    losal numeric,
    hisal numeric
);

insert into salgrade values (1, 700, 1200);
insert into salgrade values (2, 1201, 1400);
insert into salgrade values (3, 1401, 2000);
insert into salgrade values (4, 2001, 3000);
insert into salgrade values (5, 3001, 9999);
--員工表
emp員工表(empno員工號/ename員工姓名/job工作/mgr上級編號/hiredate受僱日期/sal薪金/comm佣金/deptno部門編號)
工資 ＝ 薪金 ＋ 佣金
1.表自己跟自己連線
create table emp (
    empno numeric(4) not null,
    ename varchar(10),
    job varchar(9),
    mgr numeric(4),
    hiredate datetime,
    sal numeric(7, 2),
    comm numeric(7, 2),
    deptno numeric(2)
);
insert into emp values (7369, 'SMITH', 'CLERK', 7902, '1980-12-17', 800, null, 20);
insert into emp values (7499, 'ALLEN', 'SALESMAN', 7698, '1981-02-20', 1600, 300, 30);
insert into emp values (7521, 'WARD', 'SALESMAN', 7698, '1981-02-22', 1250, 500, 30);
insert into emp values (7566, 'JONES', 'MANAGER', 7839, '1981-04-02', 2975, null, 20);
insert into emp values (7654, 'MARTIN', 'SALESMAN', 7698, '1981-09-28', 1250, 1400, 30);
insert into emp values (7698, 'BLAKE', 'MANAGER', 7839, '1981-05-01', 2850, null, 30);
insert into emp values (7782, 'CLARK', 'MANAGER', 7839, '1981-06-09', 2450, null, 10);
insert into emp values (7788, 'SCOTT', 'ANALYST', 7566, '1982-12-09', 3000, null, 20);
insert into emp values (7839, 'KING', 'PRESIDENT', null, '1981-11-17', 5000, null, 10);
insert into emp values (7844, 'TURNER', 'SALESMAN', 7698, '1981-09-08', 1500, 0, 30);
insert into emp values (7876, 'ADAMS', 'CLERK', 7788, '1983-01-12', 1100, null, 20);
insert into emp values (7900, 'JAMES', 'CLERK', 7698, '1981-12-03', 950, null, 30);
insert into emp values (7902, 'FORD', 'ANALYST', 7566, '1981-12-03', 3000, null, 20);
insert into emp values (7934, 'MILLER', 'CLERK', 7782, '1982-01-23', 1300, null, 10);

1. 條件 where > < = >= <= select * from emp where sal > 3000; --大於3000 select * from emp where sal = 5000; --等於5000 select * from emp where sal <> 5000; --不等於5000

2. 模糊查詢 like select * from emp where ename like '%S%'; --查出ename中包含S的資料 select * from emp where ename like 'S%'; --查出ename中S開頭的資料 select * from emp where ename like '%S'; --查出ename中S結尾的資料 select * from emp where ename like '_o%'; --第二個字元為o的字元，佔位符: _

3. 排序 select * from emp order by sal; --預設升序 select * from emp order by sal asc; --asc升序 select * from emp order by sal desc; --desc降序 select * from emp order by deptno asc,sal desc; --按照deptno升序，按照sal降序

4. 限制多少行 select * from emp limit 10; select * from emp order by deptno asc,sal desc limit 10;

5. 聚合 (group by) 聚合函式 (sum count avg max min) select deptno,sum(sal) sa sumsal from emp group by deptno having sum(sal) > 10000; –檢視各個部門所有的人工資總和

6. group by欄位必須出現在select語句中 select deptno,job,sum(sal) sa sumsal from emp group by deptno,job; – group by 欄位必須出現在select欄位

7. 數量 最大值等 select count(*) from emp; select max(sal) from emp;

8. 組合 順序

   select 
   deptno,job,sum(sal) as sumsal 
   from emp 
   where job = 'SALESMAN' 
   group by deptno,job 
   having sum(sal) >3000 
   order by sum(sal) desc 
   limit 1;
   

9. as別名 sum(sal) as sumsal

10. union

    a表
    id,name,address
    1,zhangsan,zhangsan18
    2,lisi,lisi20
    3,wangwu,wangwu24
    b表
    id,name,address
    1,zhangsan,zhangsan18
    2,lilei,lilei22
    3,wangwu,wangwu24
    

    去重複資料

    select * from a
    union
    select * from b;
    1,zhangsan,zhangsan18
    2,lisi,lisi20
    3,wangwu,wangwu24
    2,lilei,lilei22
    

    不去重複資料

    select * from a
    union all
    select * from b;
    
    1,zhangsan,zhangsan18
    2,lisi,lisi20
    3,wangwu,wangwu24
    1,zhangsan,zhangsan18
    2,lilei,lilei22
    3,wangwu,wangwu24
    

    select id,name from a
    union all
    select id,address from b;
    
    1,zhangsan
    2,lisi
    3,wangwu
    1,zhangsan18
    2,lilei22
    3,wangwu24