--解锁用户,需要使用dba权限 conn sys/1234 as dba; alert user scott account unlock; / --initcap方法,实现字符串首字符大写,其余字符小写,受空格,逗号等非字母符号限制 select initcap(‘hello word,da jia hao!‘) Hello from dual; --平均工资大于2000的分组 select avg_sal,deptno from (select avg(sal) avg_sal,deptno from emp group by deptno) where avg_sal >2000; having语句用法: select avg(sal),deptno from emp group by deptno having avg(sal) > 2000; / --求部门中哪些人的薪水最高 select ename,sal from emp e join (select max(sal) max_sal,deptno from emp group by deptno) t on (e.deptno = t.deptno and e.sal = t.max_sal) / --求部门平均薪水的等级 select deptno,avg_sal,grade from salgrade s join (select avg(sal) avg_sal,deptno from emp group by deptno) t on (t.avg_sal between s.losal and hisal) / --求部门平均的薪水等级 select avg(t.grade) avg_grade,t.deptno from (select ename,deptno,grade from emp e join salgrade s on (e.sal between s.losal and s.hisal)) t group by t.deptno / --雇员中哪些人是经理人 select ename from emp where empno in (select distinct mgr from emp) / --不用函数求薪水的最高值 select distinct ename,sal from emp where sal not in (select distinct e1.sal from emp e1 join emp e2 on (e1.sal <e2.sal)) / select t.ename,t.sal from (select ename,sal from emp order by sal desc) t where rownum<2(当最大薪水有多值时不对) / --求平均薪水最高的部门的部门编号 select deptno,avg_sal from (select avg(sal) avg_sal,deptno from emp group by deptno) where avg_sal = (select max(avg_sal) from (select avg(sal) avg_sal,deptno from emp group by deptno) ) 等同于: select deptno,avg_sal from (select avg(sal) avg_sal,deptno from emp group by deptno) where avg_sal = (select max(avg(sal)) from emp group by deptno) / --求平均薪水最高的部门名称 select dname from dept where deptno = ( select deptno from ( select deptno,avg(sal) avg_sal from emp group by deptno ) where avg_sal = ( select max(avg_sal) from (select avg(sal) avg_sal,deptno from emp group by deptno) ) ) / --求平均薪水的等级最低的部门的部门名称 select t.deptno,t.dname from dept t where t.deptno = ( select deptno from ( select deptno,grade,avg_sal from (select avg(sal) avg_sal,deptno from emp group by deptno) join salgrade s on (avg_sal between s.losal and s.hisal) where grade = ( select min(grade) from ( select deptno,grade,avg_sal from (select avg(sal) avg_sal,deptno from emp group by deptno) join salgrade s on (avg_sal between s.losal and s.hisal) ) ) ) ) 等同于: select t.deptno,dname,avg_sal,grade from ( select deptno,avg_sal,grade from (select avg(sal) avg_sal,deptno from emp group by deptno) t1 join salgrade s on (t1.avg_sal between s.losal and s.hisal) ) t join dept d on (t.deptno = d.deptno) where t.grade = ( select min(grade) from ( select deptno,avg_sal,grade from (select avg(sal) avg_sal,deptno from emp group by deptno) t1 join salgrade s on (t1.avg_sal between s.losal and s.hisal) ) ) / --求平均等级最低的部门名称 select t.dname from dept t where t.deptno = ( select deptno from ( select deptno,avg(grade) avg_grade from ( select e.deptno,s.grade from emp e join salgrade s on (e.sal between s.losal and s.hisal) ) group by deptno ) where avg_grade = ( select min(avg_grade) from (select deptno,avg(grade) avg_grade from (select e.deptno,s.grade from emp e join salgrade s on (e.sal between s.losal and s.hisal) ) group by deptno ) ) ) / --创建视图,首先赋予权限 conn sys/1234 as sysdba; sys不校验密码,任意密码即可。 grant create table,create view to scott; create view v_dept_avg_sal_info as select deptno,grade,avg_sal from (select deptno,avg(sal) avg_sal from emp group by deptno) t join salgrade s on (t.avg_sal between s.losal and s.hisal); 因此,求平均等级最低的部门名称可以用一下语句替换: select t.deptno,d.dname,avg_sal,grade from v_dept_avg_sal_info t join dept d on (t.deptno = d.deptno) where t.grade = (select min(grade) from v_dept_avg_sal_info); / --求部门经理人中平均薪水最低的部门名称(经理人指empno存在于mgr中的员工) select dname, t.deptno, avg_sal from (select deptno, avg(sal) avg_sal from emp where empno in (select distinct mgr from emp where mgr is not null) group by deptno) t join dept d on (d.deptno = t.deptno) where t.avg_sal = (select min(avg_sal) from (select deptno, avg(sal) avg_sal from emp where empno in (select distinct mgr from emp where mgr is not null) group by deptno)) 创建视图v_mgr_sal_info,如下: create view v_mgr_sal_info as select deptno, avg(sal) avg_sal from emp where empno in (select distinct mgr from emp where mgr is not null) group by deptno; select dname, t.deptno, avg_sal from v_mgr_sal_info t join dept d on (d.deptno = t.deptno) where t.avg_sal = (select min(avg_sal) from v_mgr_sal_info); / --求比普通员工的最高薪水还高的经理人名称: select ename from emp where empno in (select distinct mgr from emp where mgr is not null) and sal > (select max(sal) from emp where empno not in (select distinct mgr from emp where mgr is not null)) / --删除用户 drop user mc cascade; --备份用户 backup scott exp --创建用户 create user mc identified by 1234 default tablespace quota 10M on users; --赋予权限 grant create session,create table,create view to mc; --导入数据 imp --快速备份表,即创建一个一样的表 create table dept1 as select * from dept; --求薪水值最高的前五名雇员; select ename,sal from (select ename,sal from emp order by sal desc ) where rownum<6; / --求薪水值第六名到第十名的雇员; select ename,sal from (select ename,sal,rownum r from (select ename ,sal from emp order by sal desc) ) where r>5 and r <11; / /* * * 有3个表S,C,SC * S(SNO,SNAME)代表(学号,姓名); * C(CNO,CNAME,CTEACHER)代表(课号,课名,教师) * SC(SNO,CNO,SCGRADE)代表(学号,课号,成绩) * 问题:1,找出没选过“黎明”老师的所有学生姓名。 * 2,列出2门以上(含2门)不及格学生姓名及平均成绩。 * 3,既学过1号课程又学过2号课程所有学生的姓名。 * 请用标准SQL语言写出答案。 */ 答案: 1, select sname from s join sc on (s.sno = sc.sno) join c on (c.cno = sc.cno) where c.cteacher <> ‘黎明‘; 2, --学生姓名 select sname from s where s.sno in ( select sno from sc where sc.scgrade < 60 group by sco having count(*) >=2 ); --平均成绩 select avg(scgrade) from sc where sc.sno in ( select sno from sc where sc.scgrade < 60 group by sco having count(*) >=2 ) group by sc.sno; 3, select sname from s where s.sno in (select sno from sc where sc.cno =1 and sno in ( selcet distinct sno from sc where cno = 2 ) ); -- 一个事务(transaction)起始于一条dml语句(insert,update,delete),终止于①commit语句;②ddl语句(create,drop)和dcl语句(grant,remove); 正常断开连接时,transaction自动提交,非正常断开连接,transaction自动回滚。 --创建一张学生表 --约束类型:不为空约束,主键约束,外键约束,唯一性约束,check约束 create table stu1 --字段级约束条件 ( id number(6), name varchar2(20) constraint stu_name_nn not null,--不为空约束 sex number(1), age number(3), sdate date, grade number(2) default 1, class number(4) references class(id),--外键约束,外键约束被参考条件必须是主键 email varchar2(50) unique --唯一约束条件 ); create table stu ( id number(6) primary key,--主键约束 name varchar2(20) constraint stu_name_nn not null,--不为空约束 sex number(1), age number(3), sdate date, grade number(2) default 1, class number(4), email varchar2(50), constraint stu_name_email_uni unique(name,email), --表级约束 constraint stu_class_fk_foregin key (class) references class(id) ); create table class ( id number(4) primary key, name varchar2(20) not null ); alert table stu add(addr varchar2(100)); alert table stu drop (addr); alert table stu modify (addr varchar2(120)); alert table stu add constraint stu_class_fk foreign key (class) references class(id); --创建与删除索引 create index idx_stu_email on stu (email); drop index idx_stu_email; / 三范式: ①要有主键,列不可分; ②不能存在部分依赖;(联合主键情况下,非主键列不能部分依赖于主键)即每张表只描述一件事 ③确保每列都和主键列直接相关,而不是间接相关。 --pl/sql结构化语言 --变量声明的规则: 1,变量名不能使用保留字,如from、select等; 2,第一个字符必须是字母; 3,变量名最多包含30个字符; 4,不要与数据库的表或者列同名; 5,每一行只能声明一个变量。 --常用变量类型: 1,binary_integer,整数,主要用来计数而不是用来表示字段类型; 2,number,数字类型; 3,char,定长字符串; 4,varchar2,变长字符串; 5,date,日期; 6,long,长字符串,最长2GB; 7,boolean,布尔类型,可以取值为true、false和null值。 --最简单的语句块 begin dbms_output.put_line(‘HelloWorld‘); end; / 在dos命令窗口输出命令: set serveroutput on; --简单的PL/SQL语句块 declare v_name varchar2(20); begin v_name := ‘myname‘; dbms_output.put_line(v_name); end; / --异常处理 declare v_num number := 0; begin v_num := 2/v_num; dbms_output.put_line(v_num); exception when others then dbms_output.put_line(‘error‘); end; / --变量声明 declare v_temp number(1); v_count binary_integer := 0; v_sal number(7,2) := 4000.00; v_date date := sysdate; v_pi constant number(3,2) := 3.14; v_valid boolean := false; v_name varchar2(20) not null := ‘MyName‘; begin dbms_output.put_line(‘v_temp value:‘ || v_sal); end; / 注意:dbms_output.put_line命令不能打印布尔类型。 --变量声明,使用%type属性 declare v_empno number(4); v_empno2 emp.empno%type; v_empno3 v_empno2%type; begin dbms_output.put_line(‘Test‘); end; / --Table变量类型,相当于java中的数组。 declare type type_table_emp_empno is table of emp.empno%type index by binary_integer; v_empnos type_table_emp_empno; begin v_empnos(0) := 7369; v_empnos(2) := 7839; v_empnos(-1) := 9999; dbms_output.put_line(v_empnos(-1)); end; / --Table类型实例讲解 使用记录类型变量只能保存一行数据,这限制了SELECT语句的返回行数,如果SELECT语句返回多行就会错。Oracle提供了另外一种自定义类型,也就是表类型,它是对记录类型的扩展,允许处理多行数据,类似于表。 创建表类型的语法如下: TYPE table_name IS TABLE OF data_type [ NOT NULL ] INDEX BY BINARY_INTEGER ; 语法说明如下: --table_name 创建的表类型名称。 --IS TABLE 表示创建的是表类型。 --data_type 可以是任何合法的PL/SQL数据类型,例如varchar2。 --INDEX BY BINARY_INTEGER 指定系统创建一个主键索引,用于引用表类型变量中的特定行。 使用表类型的例子: 例一:直接对表类型变量赋值 declare type my_emp is table of scott.emp%rowtype index by binary_integer; new_emp my_emp; begin new_emp(1).empno:=6800; new_emp(1).ename:=‘tracy‘; new_emp(1).job:=‘clerk‘; new_emp(1).sal:=2500; new_emp(2).empno:=6900; new_emp(2).ename:=‘luck‘; new_emp(2).job:=‘manager‘; new_emp(2).sal:=4000; dbms_output.put_line(new_emp(1).empno ||‘,‘||new_emp(1).ename||‘,‘||new_emp(1).job|| ‘,‘||new_emp(1).sal); dbms_output.put_line(new_emp(2).empno ||‘,‘||new_emp(2).ename||‘,‘||new_emp(2).job|| ‘,‘||new_emp(2).sal); end; / 例二:使用表类型变量的方法:变量名.方法名[索引号] declare type my_emp is table of scott.emp%rowtype index by binary_integer; new_emp my_emp; begin new_emp(1).empno:=6800; new_emp(1).ename:=‘tracy‘; new_emp(1).job:=‘clerk‘; new_emp(1).sal:=2500; new_emp(2).empno:=6900; new_emp(2).ename:=‘luck‘; new_emp(2).job:=‘manager‘; new_emp(2).sal:=4000; dbms_output.put_line(new_emp.first||‘,‘||new_emp.count||‘,‘||new_emp.last); dbms_output.put_line(new_emp(1).empno ||‘,‘||new_emp(1).ename||‘,‘||new_emp(1).job|| ‘,‘||new_emp(1).sal); dbms_output.put_line(new_emp(2).empno ||‘,‘||new_emp(2).ename||‘,‘||new_emp(2).job|| ‘,‘||new_emp(2).sal); --new_emp.delete(1); dbms_output.put_line(new_emp.next(1)); end; // 例三:与游标结合使用 declare type my_emp is table of scott.emp%rowtype index by binary_integer; new_emp my_emp; v_num number:=0; cursor cur_emp is select empno,ename,job,sal from scott.emp; begin for v_emp in cur_emp loop v_num:=v_num+1; select * into new_emp(v_num) from scott.emp where ename=v_emp.ename; end loop; for i in 1..new_emp.count loop dbms_output.put_line(new_emp(i).empno ||‘,‘||new_emp(i).ename||‘,‘||new_emp(i).job|| ‘,‘||new_emp(i).sal); end loop; end; / 注意:不能直接对表变量赋值:select * into new_emp from scott.emp where deptno=30; 这种赋值方法是错的,赋值需要使用下标,如上面的的例子。 --Record变量类型 declare type type_record_dept is record ( deptno dept.deptno%type, dname dept.dname%type, loc dept.loc%type ); v_temp type_record_dept; begin v_temp.deptno := 50; v_temp.dname := ‘aaaa‘; v_temp.loc := ‘bj‘; dbms_output.put_line(v_temp.deptno || ‘ ‘ || v_temp.dname); end; / --使用%rowtype声明record变量 declare v_temp dept%rowtype; begin v_temp.deptno := ‘50‘; v_temp.dname := ‘aaaa‘; v_temp.loc := ‘bj‘; dbms_output.put_line(v_temp.deptno || ‘ ‘ || v_temp.dname); end; / --sql语句的运用 --select语句 declare v_ename emp.ename%type; v_sal emp.sal%type; begin select ename,sal into v_ename,v_sal from emp where empno = 7369; dbms_output.put_line(v_ename || ‘ ‘ || v_sal); end; / --select语句 declare v_emp emp%rowtype; begin select * into v_emp from emp where empno = 7369; dbms_output.put_line(v_emp.ename); end; / --insert语句 declare v_deptno dept.deptno%type := 50; v_dname dept.dname%type := ‘aaaa‘; v_loc dept.loc%type := ‘bj‘; begin insert into dept values(v_deptno,v_dname,v_loc); commit; end; / --update语句 declare v_deptno emp.deptno%type := 50; v_count number; begin update emp set sal = sal/2 where deptno = v_deptno; --select deptno into v_deptno from emp where empno = 7369; --select count(*) into v_count from emp; dbms_output.put_line(sql%rowcount || ‘条记录被影响‘); commit; end; / 注意:sql代表刚刚执行过的语句,rowcount代表刚执行过的语句影响的记录。 --PL/SQL中执行DDL语句 begin execute immediate ‘create table T (nnn varchar2(20) default ‘‘aaa‘‘ )‘; end; / --if语句 --取出7369的薪水,如果<1200,则输出‘low‘,如果<2000,则输出‘middle‘,否则‘high‘; declare v_sal emp.sal%type; begin select sal into v_sal from emp where empno = 7369; if(v_sal<1200) then dbms_output.put_line(‘low‘); elsif(v_sal<2000) then dbms_output.put_line(‘middle‘); else dbms_output.put_line(‘high‘); end if; end; / --循环 --loop when循环,相当于java中的do..while循环 declare i binary_integer := 1; begin loop dbms_output.put_line(i); i := i+1; exit when (i >= 11); end loop; end; / --while循环 declare j binary_integer := 1; begin while j < 11 loop dbms_output.put_line(j); j := j+1; end loop; end; / --for循环 declare k binary_integer := 1; begin for k in 1..10 loop dbms_output.put_line(k); end loop; end; / declare k binary_integer := 1; begin for k in reverse 1..10 loop --逆序 dbms_output.put_line(k); end loop; end; / --错误处理 declare v_temp number(4); begin select empno into v_temp from emp where deptno = 10; exception when too_many_rows then dbms_output.put_line(‘太多记录了‘); when others then dbms_output.put_line(‘没数据‘); end; / declare v_temp number(4); begin select empno into v_temp from emp where empno = 2222; exception when no_data_found then dbms_output.put_line(‘没数据‘); end; / --创建错误日志 create table errorlog ( id number primary key, errcode number, errmsg varchar2(1024), errdate date ); / create sequence seq_errorlog_id start with 1 increment by 1; / declare v_deptno dept.deptno%type := 10; v_errcode number; v_errmsg varchar2(1024); begin delete from dept where deptno = v_deptno; commit; exception when others then rollback; v_errcode := SQLCODE; v_errmsg := SQLERRM; insert into errorlog values (seq_errorlog_id.nextval,v_errcode,v_errmsg,sysdate); commit; end; / --游标 declare cursor c is --声明游标 select * from emp; v_emp c%rowtype; begin open c; --打开游标 fetch c into v_emp; dbms_output.put_line(v_emp.ename); close c; --关闭游标 end; / --游标,循环 declare cursor c is select * from emp; v_emp c%rowtype; begin open c; loop fetch c into v_emp; exit when (c%notfound); dbms_output.put_line(v_emp.ename); end loop; close c; end; / --while循环 declare cursor c is select * from emp; v_emp emp%rowtype; begin open c; fetch c into v_emp; while (c%found) loop dbms_output.put_line(v_emp.ename); fetch c into v_emp; end loop; close c; end; / --for循环 declare cursor c is select * from emp; begin for v_emp in c loop dbms_output.put_line(v_emp.ename); end loop; end; / --带参数的游标 declare cursor c(v_deptno emp.deptno%type, v_job emp.job%type) is select ename,sal from emp where deptno = v_deptno and job = v_job; begin for v_temp in c(30,‘CLERK‘) loop dbms_output.put_line(v_temp.ename); end loop; end; / --可更新的游标 declare cursor c is select * from emp2 for update; begin for v_temp in c loop if (v_temp.sal < 2000) then update emp2 set sal = sal * 2 where current of c; elsif (v_temp.sal = 5000) then delete from emp2 where current of c; end if; end loop; commit; end; / --oracle集合类型的first、next、prior、 last方法 创建一个存储过程,用于产生oracle三种集合类型的数据 create or replace procedure plch_main is TYPE NESTED_T IS TABLE OF NUMBER;--嵌套表类型 TYPE ASSOCIATIVE_T IS TABLE OF NUMBER INDEX BY BINARY_INTEGER; --索引表类型 TYPE VARRAYS_T IS VARRAY(10) OF NUMBER; --变长数组类型 lst_nested nested_t:=nested_t(-2000,null,3500); lst_associative associative_t;--索引表类型的集合不能直接赋值 可以从其特性来理解(可以是稀疏排列的) lst_varrays varrays_t:=varrays_t(-2000,null,3500); begin lst_associative(1):=-2000; lst_associative(3):=null;--注意,这里没有lst_associative数组第二个元素 lst_associative(4):=3500; dbms_output.put_line(‘以下为嵌套表的输出内容:‘); dbms_output.put_line(‘lst_nested(1) :‘||lst_nested(1)); dbms_output.put_line(‘lst_nested(2) :‘||lst_nested(2)); dbms_output.put_line(‘lst_nested(3) :‘||lst_nested(3)); dbms_output.put(‘lst_nested.first-1:‘); dbms_output.put_line(lst_nested.first-1); dbms_output.put_line(‘lst_nested.first :‘||lst_nested.first); dbms_output.put_line(‘lst_nested.prior(1):‘||lst_nested.prior(1)); dbms_output.put_line(‘lst_nested.next(1):‘||lst_nested.next(1)); dbms_output.put_line(‘lst_nested.next(2):‘||lst_nested.next(2)); dbms_output.put_line(‘lst_nested.next(3):‘||lst_nested.next(3)); dbms_output.put_line(‘lst_nested.last :‘||lst_nested.last); dbms_output.put_line(‘以下为索引表的输出内容:‘); dbms_output.put_line(‘lst_associative(1) :‘||lst_associative(1)); dbms_output.put_line(‘lst_associative(3) :‘||lst_associative(3)); dbms_output.put_line(‘lst_associative(4) :‘||lst_associative(4)); dbms_output.put(‘lst_associative.first-1:‘); dbms_output.put_line(lst_associative.first-1); dbms_output.put_line(‘lst_associative.first :‘||lst_associative.first); dbms_output.put_line(‘lst_associative.prior(1):‘||lst_associative.prior(1)); dbms_output.put_line(‘lst_associative.next(1):‘||lst_associative.next(1)); dbms_output.put_line(‘lst_associative.next(2):‘||lst_associative.next(2)); dbms_output.put_line(‘lst_associative.next(4):‘||lst_associative.next(4)); dbms_output.put_line(‘lst_associative.last :‘||lst_associative.last); dbms_output.put_line(‘以下为变长数组的输出内容:‘); dbms_output.put_line(‘lst_varrays(1) :‘||lst_varrays(1)); dbms_output.put_line(‘lst_varrays(2) :‘||lst_varrays(2)); dbms_output.put_line(‘lst_varrays(3) :‘||lst_varrays(3)); dbms_output.put(‘lst_varrays.first-1:‘); dbms_output.put_line(lst_varrays.first-1); dbms_output.put_line(‘lst_varrays.first :‘||lst_varrays.first); dbms_output.put_line(‘lst_varrays.prior(1):‘||lst_varrays.prior(1)); dbms_output.put_line(‘lst_varrays.next(1):‘||lst_varrays.next(1)); dbms_output.put_line(‘lst_varrays.next(2):‘||lst_varrays.next(2)); dbms_output.put_line(‘lst_varrays.next(3):‘||lst_varrays.next(3)); dbms_output.put_line(‘lst_varrays.last :‘||lst_varrays.last); end; / 存储过程编译成功,以下调用并查看结果。 特别注意三种数组中第一个元素的prior方法、最后一个元素的next方法都是可以执行出来的; 并且索引表类型中未定义的元素序列也有prior、next方法。 SQL> exec plch_main; 以下为嵌套表的输出内容: lst_nested(1) :-2000 lst_nested(2) : lst_nested(3) :3500 lst_nested.first-1:0 lst_nested.first :1 lst_nested.prior(1): lst_nested.next(1):2 lst_nested.next(2):3 lst_nested.next(3): lst_nested.last :3 以下为索引表的输出内容: lst_associative(1) :-2000 lst_associative(3) : lst_associative(4) :3500 lst_associative.first-1:0 lst_associative.first :1 lst_associative.prior(1): lst_associative.next(1):3 lst_associative.next(2):3 lst_associative.next(4): lst_associative.last :4 以下为变长数组的输出内容: lst_varrays(1) :-2000 lst_varrays(2) : lst_varrays(3) :3500 lst_varrays.first-1:0 lst_varrays.first :1 lst_varrays.prior(1): lst_varrays.next(1):2 lst_varrays.next(2):3 lst_varrays.next(3): lst_varrays.last :3 PL/SQL procedure successfully completed .first方法是数组中第一个元素的下标值(序列值) .prior(n)方法是数组中第n个元素的前一个元素的下标值(序列值)
时间: 2024-10-24 05:34:55