SQL語句 oracle限制和排序
2.1 where
作用：限制行的查詢
例2.1.1
SQL> select dname from scott.dept
where deptno = 10;
2.2 Between
Between
100 and 103 :包含100和103
例2.2.1
SQL>select DNAME from scott.dept
where deptno between 10 and 30;
例2.3.1
SQL>select * from scott.dept; DEPTNO DNAME LOC 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON 41 A%%%%%%% A 42 A%_%%%%% B SQL>select dname from scott.dept where deptno in (40,42); DNAME -------------- OPERATIONS A%_%%%%%
2.4 like
2.4.1 作用：模糊查詢，搜尋條件可以包含文字字元或數字
1）%表示零或多個字元
2）_表示一個字元
例2.4.1
SQL>select dname from scott.dept
where deptno like '1%';
2.4.2 單引號轉義符
Escapez:轉義%與_匹配字元本來的含義
方法一：SQL> select ename||q'['s sal is ]'||sal info from scott.emp;
方法二：
SQL> select ename||'''s sal is '||sal from scott.emp;
例2.4.2
SQL> select ename||'''s sal is '||sal from scott.emp; ENAME||'''SSALIS'||SAL ------------------------------------------------------------ SMITH's sal is 800 ALLEN's sal is 1600 WARD's sal is 1250 JONES's sal is 2975 MARTIN's sal is 1250 BLAKE's sal is 2850 CLARK's sal is 2450 SCOTT's sal is 3000 SQL> select * from scott.dept; DEPTNO DNAME LOC 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON
例2.4.3
SQL> insert into
scott.dept values (41,'A%%%%%%%','A');
1 row
created.
SQL> select * from scott.dept;
DEPTNO DNAME LOC
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
41 A%%%%%%% A
例2.4.4
SQL> insert into
scott.dept values (42,'A%_%%%%%','B');
1 row
created.
SQL>select * from scott.dept;
DEPTNO DNAME LOC
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
41 A%%%%%%% A
42 A%_%%%%% B
6 rows
selected.
2.4.3 ~
轉義符:~的下一個字元如果是%，這個百分號是真實的百分號，沒有特殊的含義
例 2.4.5查詢A%_開頭的
SQL>select * from scott.dept where dname like 'A~%~_%' escape '~';
DEPTNO DNAME LOC
42 A%_%%%%% B
2.5 OR
例2.5.1
SQL>select loc from scott.dept
where deptno >= 10
or dname like 'A%';
2.6 NOT IN
例2.6.1
SQL>select dname from scott.dept
where deptno not in (10,40);
DNAME
--------------
RESEARCH
SALES
A%%%%%%%
A%_%%%%%
2.7 || 連線運算子
SQL> select * from scott.dept;
DEPTNO DNAME LOC
----------
-------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
41 A%%%%%%% A
42 A%_%%%%% B
SQL>select
dname ||' is '||deptno
as "name" from scott.dept;
name
----------------------------------------------------------
ACCOUNTING is 10
RESEARCH is 20
SALES is 30
OPERATIONS is 40
A%%%%%%% is 41
A%_%%%%% is 42
2.8 DISTINCT去除重複的行
用法：select distinct 列名 from 表名
例2.8.1
SQL>select id from student1;
ID
----------
1
2
3
4
5
6
7
8
9
9
10 rows
selected.
SQL>select distinct id from student1;
ID
----------
1
6
2
4
5
8
3
7
9
9 rows
selected.
2.9 在sqlplus 環境裡執行作業系統命令
用法：
！clear
host 命令
例2.9.1
SQL>!clear
SQL>host echo hehe
hehe
例2.9.2
SQL>host pwd
/home/oracle/Desktop
例2.9.3
2.10 and
例2.10.1
2.11 or
2.12 規則優先
2.13 Order by排序
特點：放在select 語句末尾，預設升序（asc）,降序是desc
2.13.1 降序
2.13.2用列別名排序
2.13.3 用列所在數字位排序
2.13.4 多列排序
2.14 替代變數
特點：臨時變數用&，呼叫替代變數用&&，變數中的字元和日期要用單引號引起來。
用法：select 列名 from
表名 where 列名 = &新列名；
用途：
where 子句
order 子句
列表達式
表名
整個語句
例2.14.1
SQL>select id,name
2 fromstudent
3 where id = &stid
4 ;
Enter
value for stid: 2
old 3: where id = &stid
new 3: where id = 2
ID NAME
----------
--------------------
2
xixi
2.15 define建立和分配一個值到一個變數
undefine取消已定義的變數
例2.15.1
2.16 set verify on|off 變數替換的過程新舊值是否顯示
例2.16.1
2.17建立使用者
命令格式：create user c##建立的使用者名稱 identified by oracle
SQL>create user c##xigua identified by oracle;
User
created.
2.18 IS(NOT) NULL空值判斷
用法：select 條件 f rom 表名 where 列名 is(is
not) null;
例2.18.1
SQL>select * from student
2 where name is not null;
ID NAME SEX AGE COURSE SCORE
1 LISA girl 21 math 80
2 xixi girl 22 english 90
3 Kris Wu boy 20 langauage 88
4 jen girl 25 history 70
5 hz boy 22 computer 60
6 xfy girl 21 computer 99
7 yy boy 22 math 54
8 lanxi girl 21 english 60
9 hony boy 22 history 56
9 rows
selected.