sql, plsql 总结

 

/*
 *====================================== basic sql ==========================================
 */
 
-- Merge --
merge into copy_emp as ac
using employees e
on (c.employee_id = employee_id)
when matched then
    update set
    c.first_name = e.first_name
    c.last_name = e.last_name
    c.department_id = e.department_id
when not matched then
    insert values(e.employee_id, e.first_name, e.last_name, e.department_id)

-- alter table --
alter table dep80
add(job_id varchar(8))

alter table dep80
modify(job_id varchar(30))

alter table dep80
drop(job_id)

alter table dep80
set unused(job_id)

-- reaname --
rename dept to detail_dept

-- truncate --
truncat table detial_dept

-- comment --
comment on table dept IS 'department information'
comment on dept.deptno IS 'department number'

-- constraint , not null, unique, primary key, foreign key, check --
create table employees (
    employee_id        NUMBER(6),
    job_id            VARCHAR2(10) NOT NULL,
    
    constraint emp_id_pk PRIMARY KEY(employee_id)
)

alter table employees
    add constraint emp_manager_fk FOREIGN KEY(manager_id)
    REFERENCES employee(employee_id)

alter table employees
    drop constraint emp_manager_fk [cascade]

alter table employees
    disable constraint emp_manager_fk[cascade]

alter table employees
    enable constraint emp_manager_fk

alter table employees
    drop (column1, column2) [cascade constraints]

-- view --
create or replace view emp_view as select deptno, dname, loc from dept
drop view emp_view

-- sequence --
create sequence seq_emp
increment by 1
start with 0
maxvalue 20000000
minvalue 0
nocycle
nocache

-- index --
create index ind_emp on dept(deptno, dname)

-- synonym --
create public synonym dept for scott.dept
-- 2种方法: 例如 object 在 hr 下, scott 想要访问 hr 下的 table department.
-- 1. 在 scott 模式下, create synonym department for hr.department
-- 2. 在 hr 模式下, create synonym scott.department for department , 注意这种含义是 hr 用户代替 scott
-- 用户在 scott 模式下创建了别名, scott.department 这个表示是在 scott模式下, 所以在 scott 模式下就直接
-- 有了这样一个别名.

-- create user --
create user leon_master identified by leon
alter user leon_master identified by master ( 修改密码 )

-- grant privilege --
grant dba to leon_master
grant create session, create table, create sequence to scott ( to role )
grant manager(role) to leon_master
grant update(deptname, location_id) on departments to scott, manager

-- role --
create role manager;
grant create session, create table, create sequence to manager;

-- revoke --
revoke create session from scott
revoke update(deptname, location_id) on department from scott, manager

-- database link --
create public database link mes20
connect to <被链接数据库用户名> identified by <被链接数据库密码>
using 'ASDF'

/*
tnsnames >>>
ASDF, ASDF2 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 109.106.13.25)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = 109.106.13.22)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = 109.106.13.26)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ASDF)
    )
  )
*/
-- relation sub query --
select column1, column2
FORM table1 outer
where column1 operator ( select column1 from table2 where expr1 = outer.exp2);

select column1, column2
from table1 outer
where exists ( select column1 from table2 where expr1 = outer.exp2);

update table1 als_1
set column = ( select expression from table2 als_2 where als_1.column = als_2.column);

delete from table1 als_1
where column operator ( select expression from table2 als_2 where als_1.column = als_2.column);

-- Hierarchical retrieve --

select substr(sys_connect_by_path(ENAME,'->'), 3) EMPLOYEE from EMP
connect by prior EMPNO = MGR
start with ename = '小董'

-- 首先这个查询有一个 connect by prior EMPNO=MGR, 这是一个连接条件, 从 start with 开始找到第一行数据,
-- 然后根据连接条件来进行. 向后遍历. 翻译过来就是, 先从小董开始, 然后小董的 empno 作为父层次 = manager
-- 向后依次遍历.

/*
 * =========================================== plsql =========================================
 */
 
-- 系统绑定变量 可以直接在 sqlplus 环境中定义
variable g_salary NUMBER 
-- 注意此变量不同于一般意义的plsql变量, 这个是在环境中定义的类似环境变量

-- PL/SQL 定义变量
declare    v_depno number(2) not null := 100;
declare c_comn constant number := 1400;
declare v_location varchar(20) := 'hello world';
declare v_name employees.lastname%TYPE;
declare v_balance number(10,2);
declare v_min_balance v_balance%TYPE :=10; -- 参照上一个定义 v_balance
-- declare v_home = q'[tom's home]' -- 注意是以双引号内的形式, 实际环境中, 不需要双引号
declare l_right_now DATE NOT NULL DEFAULT SYSDATE;


-- 在 PL/SQL 中 sql 部分不需要冒号 :
declare v_bonus NUMBER(6);
begin
    select salary * 0.01
    INTO v_bouns
    FROM employees
    WHERE emp_id = '200912';
end;

-- 游标 --
declare cursor cursor_name IS
    select_statement;
open cursor_name
fetch cursor_name into variable1, varibal2
close cursor_name 
-- 以上4步骤, 分别为定义游标, 打开游标, 取出游标, 关闭游标

-- 游标属性 --
cursor_name%isopen
cursor_name%notfound
cursor_name%found
cursor_name%rowcount

-- 隐式游标举例 --
Function book_title (isbn_in IN books.isbn%TYPE)
return books.title%type
IS
    return_value    book.title%type;
BEGIN
    SELECT     title
    into    return_value
    from    books
   where    isbn = isbn_in;
   
    return    return_value;
    
    exception
        when no_date_found
        then
            return null;
        when too_many_rows
        then
            errpkg.record_and_stop ('Data integrity error for:' || isbn_in);
            raise;        
END;

-- 显示游标举例 --
Function jealousy_level (
    NAME_IN    IN    friends.NAME%TYPE)    RETURN    NUMBER
AS
    cursor jealousy_cur
    IS
        select location from friends
        where name = UPPER(name_in);
        
    jealousy_rec    jealousy_cur%ROWTYPE;    
    retval    NUMBER;
BEGIN
    OPEN jealousy_cur;
    
    fetch jealousy_cur into    jealousy_rec;
    
    IF jealousy_cur%found then
        if jealousy_rec.location = 'PUERTO RICO' THEN
            retval := 10;
        elsif jealousy_rec.location = 'CHICAGO' THEN
            retval := 1;
        end if;
    end if;
    
    close jealousy_cur;
    
    return retval;
EXCEPTION
    when others then
        if jealousy_cur%isopen then
            close jealousy_cur;
        end if;            
END;

-- 游标变量 --
TYPE cursor_type_name IS REF CURSOR [RETURN return type];

TYPE company_curtype IS REF CURSOR RETURN company%ROWTYPE;  -- 强类型

TYPE generic_curtype IS REF CURSOR;                            -- 弱类型

-- 从 oracle 9i 开始, 数据库已经替我们定义好了一个弱类型, 直接用就可以了
declare my_cursor SYS_RECURSOR;

-- 声明游标变量的方法
cursor_name cursor_type_name;

-- 打开游标变量
open cursor_name FOR select_statement;
-- 从游标变量获取数据, 同静态游标一样
FETCH cursor_variable_name INTO record_name;
FETCH cursor_variable_name INTO varibale_name, variable_name...;
    

-- 游标表达式
CURSOR( subquery )    
    
-- 参数化 游标 --  参数的类型只能是 in 类型
declare
    v_department    classes.department%type;
    v_course        classes.course%type;
    
    cursor    c_classes is
    select * from classes
    where department = v_department
    and course = v_course;

declare
    cursor c_classes(p_department classes.department%type, p_course classes.course%type) is
    select * from classes
    where department = v_department
    and course = v_course;
open c_classes('HIS', 101);

-- 游标中的 for update 语句, 加锁, 默认的游标是不会加锁的 --
-- 如果此时该表已经被加锁, 那么这个游标将无限期的被挂起, 直到该表所已经解开, 而 NOWAIT 语句表示不等挂起
-- 如果发现这个表已经被加锁, 直接会提示一个错误, 个人感觉 NOWAIT 好一点

declare
    v_NumCredits    classes.num_credites%type;
    
    cursor c_RegisteredStudents IS
    select * from students
    where id in ( select student_id
                    from registered_students
                    where department = ’HIS‘
                    and course = 101)
    for update of current_credits;  -- one column
    
begin
    for v_studentInfo in c_RegisteredStudents
    loop
        select num_credits
        into v_NumCredits
        from classes
        where department = 'HIS'
        and course = 101;
        
        update students
            set current_credits = current_credits + v_NumCredits
            where current of c_RegisteredStudents  -- 修改当前行的 column 值
    end loop;
end;

-- 注意 commit; 操作会释放锁, 所以如果你将 commit 写在 for 循环里的话, 那么再没有完成的情况下就释放锁,
-- 会出现错误提示 ORA-1002： fetch out of sequence

declare
    cursor c_AllStudents IS
    select * from students
    for update;        -- 注意, 这只有 for update, 所以所有的列都被加锁
    
    v_StudentInfo    c_AllStudents%ROWTYPE;
begin
    open    c_AllStudents;
    FETCH c_allStudents INTO v_StudentInfo;
    -- 如果这时候使用 commit; 那么后边的记录就没有办法进行了, 所以推荐 close cursor 以后再 commit;
end;

-- 当然, 如果你非想在 for 循环里使用 commit, 做法是, 现将游标全部提取出来, 然后通过 for 循环进行修改
declare
    v_NumCredits    classes.num_credites%type;
    
    cursor c_RegisteredStudents IS
    select * from students
    where id in ( select student_id
                    from registered_students
                    where department = ’HIS‘
                    and course = 101)
    for update of current_credits;  -- one column
    
begin
    for v_studentInfo in c_RegisteredStudents
    loop
        select num_credits
        into v_NumCredits
        from classes
        where department = 'HIS'
        and course = 101;
        
        update students
            set current_credits = current_credits + v_NumCredits
            where current of c_RegisteredStudents  -- 修改当前行的 column 值
        commit;  -- 注意此时已经通过 for 循环将所有游标提取到 v_studentInfo里, 并且不能使用
                 -- where current of
    end loop;
end;

-- If statement --
IF salary >= 10000 AND salary <=20000
THEN
    give_bonus(employee_id, 1500);
ELSIF salary > 20000 AND salary <= 40000
THEN
    give_bonus(employee_id, 10000);
ELSIF salary > 40000
THEN
    give_bouns(employee_id, 400);
END IF;

-- case statement --
CASE employee_type
WHEN 'S' THEN
    award_salary_bonus(employee_id);
WHEN 'H' THEN
    award_hourly_bonus(employee_id);
WHEN 'C' THEN
    award_commissioned_bonus(employee_id);
ELSE
    RAISE invalid_employee_type;
END CASE;

CASE TRUE
WHEN salary >= 10000 AND salary <= 20000 THEN
    give_bouns(employee_id, 1500);
WHEN salary > 20000 AND salary < 40000 THEN
    give_bouns(employee_id, 1000);
ELSE
    give_bouns(employee_id, 0);
END CASE;

-- loop --

-- basic loop --
PROCEDURE display_multiple_years (
    start_year_in IN PLS_INTEGER,
    end_year_in IN PLS_INTEGER
)
IS
    l_current_year PLS_INTEGER := start_year_in;
BEGIN
    LOOP
        EXIT WHEN l_current_year > end_year_in;
        display_total_sales(l_current_year);
        l_current_year := l_current_year + 1;
    END LOOP;
END display_muliple_years;

-- for loop --
procedure display_multiple_years( start_year_in IN PLS_INTEGER, end_year_in IN PLS_INTEGER)
IS
BEGIN
    FOR l_current_year IN start_year_in .. end_year_in
    LOOP
        display_total_sales(l_current_year);
    END LOOP;
END display_multiple_years;

procedure display_multiple_years( start_year_in IN PLS_INTEGER, end_year_in IN PLS_INTEGER)
IS
BEGIN
    FOR l_current_year IN (
        select * from sales_date
        where year between start_year_in and end_year_in)
    LOOP
        display_total_sales(l_current_year);
    END LOOP;
END display_multiple_years;

-- 游标参考 for loop --

-- 一般形式的游标 --
declare 
    cursor occupancy_cur IS
    select pet_id, room_number
    from occupancy where occupid_dt = trunc(sysdate);
    
    occupancy_rec occupancy_cur%rowtype;
    
begin
    open occupancy_cur;
    loop
        fetch occupancy_cur into occupancy_rec;
        exit when occupancy_cur%notfound;
        update_bill(occupancy_rec.pet_id, occupancy_rec.room_id);
    end loop;
    close occupancy_cur;
end;

-- For loop 形式游标 --
declare 
    cursor occupancy_cur IS
    select pet_id, room_number
    from occupancy where occupid_dt = trunc(sysdate);
begin
    for occupancy_rac in occupacy_cur        -- occupancy 不用定义
    loop
        update_bill(occupancy_rec.pet_id, occupancy_rec.room_id);
    end loop;
end;

-- while loop --
procedure display_multiple_years( start_year_in IN PLS_INTEGER, end_year_in IN PLS_INTEGER)
IS
    l_current_year PLS_INTEGER := start_year_in;
BEGIN
    while (l_current_year <= end_year_in)
    LOOP
        display_total_sales(l_current_year);
        l_current_year := l_current_year + 1;
    END LOOP;
END display_multiple_years;

-- --------------------------Exception ------------------------------------------------------------
-- EXCEPTION --
-- 1.抛出异常, 用户错误, 系统错误, 内存泄露等等问题都会抛出异常
--   抛出方式, raise exception_name, raise package_name.exception_name, raise;
--     raise_application_error 也可以抛出异常, 并且可以写自己bussiness的逻辑信息
procedure raise_by_language(code_in IN PLS_INTEGER)
IS
    l_message error_table.error_string%TYPE;
BEGIN
        SELECT error_string
        INTO    l_message
        FROM    error_table
        where    error_number = code_in
        and     string_language = USERNV('LANG');
        
        RAISE_APPLICATION_ERROR(code_in, l_message);    -- 抛出异常
END;
-- 2. 捕获异常
--      异常种类, oracle定义好有名字的异常, 一共20个, 没名字的异常, 还有就是用户定义异常
--      捕获异常后, 程序不会返回到抛出异常处, 执行完捕获异常, 看是向下还是停止.
--       当处理没有命名的异常时, 可以通过以下语句来定义名称
declare
    e_emps_remaining    EXCEPTION
    PRAGMA    EXCEPTION_INIT(e_emps_remaining, -2292);
begin
    -- do something
    exception
        when e_emps_remaining then
            statement1
end;
-- 3. 内置函数
SQLCODE -- 返回一个错误代码, 如果没有错误, 返回 0
SQLERRM -- 返回错误代码对应的官方错误信息
DBMS_UTILITY.FORMAT_ERROR_BACKTRACK -- 10g 以后开始饮用, 返回一个格式化文本串(可以返回抛出异常行号)
-- ---------------------------------End Exception -------------------------------------------------

-- --------------------- 动态 sql -----------------------------------------------------------------



-- ---------------------- End 动态 sql ------------------------------------------------------------