oracle的左連接或右連接 以下是解釋，自己研究下： ------------------------------------------------------------------- 數據表的連接有: 1、內連接(自然連接): 只有兩個表相匹配的行才能在結果集中出現 2、外連接: 包括 （1）左外連接(左邊的表不加限制) （2）右外連接(右邊的表不加限制) （3）全外連接(左右兩表都不加限制) 3、自連接(連接發生在一張基表內) select a.studentno, a.studentname, b.classname from students a, classes b where a.classid(+) = b.classid; STUDENTNO STUDENTNAM CLASSNAME ---------- ---------- ------------------------------ 1 周虎 一年級一班 2 周林 一年級二班 一年級三班 以上語句是右連接： 即"(+)"所在位置的另一側為連接的方向，右連接說明等號右側的所有 記錄均會被顯示，無論其在左側是否得到匹配。也就是說上例中，無 論會不會出現某個班級沒有一個學生的情況，這個班級的名字都會在 查詢結構中出現。
反之： select a.studentno, a.studentname, b.classname from students a, classes b where a.classid = b.classid(+);
STUDENTNO STUDENTNAM CLASSNAME ---------- ---------- ------------------------------ 1 周虎 一年級一班 2 周林 一年級二班 3 鐘林達
則是左連接，無論這個學生有沒有一個能在一個班級中得到匹配的部門號， 這個學生的記錄都會被顯示。
select a.studentno, a.studentname, b.classname from students a, classes b where a.classid = b.classid;
這個則是通常用到的內連接,顯示兩表都符合條件的記錄
總之,
左連接顯示左邊全部的和右邊與左邊相同的 右連接顯示右邊全部的和左邊與右邊相同的 內連接是只顯示滿足條件的! create or replace procedure insert_procedure is begin ? insert into employee(id,username,password,birthday,email,address) values(5,'dog','dog123',to_date('2010-10-15 12:15:01','YYYY-MM-DD hh:mi:ss'),'dog@126.com','China,Henan'); end; /? create or replace procedure delete_procedure is begin ? delete from employee where id = 5; end; / create or replace procedure delete_procedure(p_id number) is begin ? delete from employee where id = p_id; end; / begin ? dbms_output.put_line('Hello, world'); end; create or replace procedure name_procedure(v_id number) is ? v_name employee.username%type; begin ? select username into v_name from employee where id = v_id; ? dbms_output.put_line('username is ' || v_name); end; / create or replace procedure name_exception_procedure(v_id number) is ? v_name employee.username%type; begin ? select username into v_name from employee where id = v_id; ? dbms_output.put_line('username is ' || v_name); exception ? when no_data_found then ??? dbms_output.put_line('根據ID找不到相關記錄'); end; / create or replace procedure name_many_procedure(v_id number) is ? v_username employee.username%type; begin ? select username into v_username from employee where id = v_id; exception ? when too_many_rows then ??? dbms_output.put_line('返回記錄數過多'); end; / create or replace procedure update_procedure(v_id in number,v_username in varchar2,v_password in varchar2) is begin ? update employee set employee.password = v_password,employee.username = v_username where employee.id = v_id; end; / create or replace function password_function(v_username in varchar2) return varchar2 is v_password employee.password%type; begin ? select employee.password into v_password from employee where employee.username = v_username; return v_password; Exception ? when no_data_found then ??? dbms_output.put_line('用戶名不存在 !'); ??? return null; end; / create or replace package sys_package is?? procedure update_procedure(v_username in varchar2); ? function select_function(v_username in varchar2) return varchar2; end; / create or replace package body sys_package is ? procedure update_procedure(v_username in varchar2) is ??? begin ????? update employee set employee.username = v_username where employee.id = 1; ??? end; ? ? function select_function(v_username in varchar2) return varchar2 is ??? v_password employee.password%type; ??? begin ????? select employee.password into v_password from employee where employee.username = v_username; ????? return v_password; ??? end; end; / declare ? type employee_record_type is ??? record(v_username employee.username%type, v_password employee.password%type, v_email employee.email%type); ? employee_record employee_record_type; begin ? select employee.username, employee.password, employee.email into employee_record from employee where employee.id = 1; ? dbms_output.put_line('username :' || employee_record.v_username || 'password :' || employee_record.v_password || 'email :' || employee_record.v_email); end; / declare ? type employee_cursor_type is ref cursor; employee_cursor employee_cursor_type; ? v_username employee.username%type; ? v_password employee.password%type; begin ? open employee_cursor for ??? select employee.username, employee.password from employee where employee.id = 5; ? loop ??? fetch employee_cursor into v_username,v_password; ? exit when employee_cursor%notfound; ??? dbms_output.put_line('username :' || v_username || 'password :' || v_password); ? end loop; ? close employee_cursor; end; / create or replace procedure if_employee_procedure(v_id number) is v_username employee.username%type; begin ? select employee.username into v_username from employee where employee.id = v_id; ? if length(v_username) < 11 then ??? update employee set employee.username = rpad(v_username, 11, 0) where employee.id = v_id; ? end if; end; / create or replace procedure if_else_employee_procedure(v_id in number) is v_username employee.username%type; begin ? select employee.username into v_username from employee where employee.id = v_id; ? if length(v_username) < 10 then ??? update employee set employee.username = rpad(v_username, 18, 0) where id = v_id; ? else ??? update employee set employee.username = rpad(v_username, 15, 0) where id = v_id; ? end if; end; / create or replace procedure loop_employee_procedure is v_id number:=6; begin ? loop ??? insert into employee values(v_id, 'ding', 'ding', to_date('2012-10-06 10:15:27','yyyy-mm-dd hh:mi:ss'), 'ding@126.com', 'China'); ? exit when v_id = 15; ? v_id:=v_id + 1; ? end loop; end; / create or replace procedure while_procedure is v_id number := 16; begin ? while v_id < 30 loop ??? insert into employee values(v_id, 'dys','dys456',to_date('1988-10-15 15:24:18','yyyy-mm-dd hh24:mi:ss'),'dys456@126.com','China ,hebei'); ??? v_id:=v_id+1; ? end loop; end; / create or replace procedure return_procedure(v_id in number,v_username out varchar2) is begin select employee.username into v_username from employee where employee.id = v_id; end; / create or replace package myPackage is ? type v_employee_cursor is ref cursor; end; / create or replace procedure ref_cursor_procedure(v_id in number,v_out_result out myPackage.v_employee_cursor) is begin ? open v_out_result for???? select * from employee where employee.id = v_id; end; / create or replace procedure fenYeProcedure(v_in_table in varchar2,v_in_pageSize in number,v_in_pageNow in number,v_out_result out myPackage.v_employee_cursor,v_out_totalRows out number,v_out_pageCount out number) is v_sql varchar2(2000); v_start_row number; v_end_row number; begin ? v_start_row:=v_in_pageSize*(v_in_pageNow-1)+1; ? v_end_row:=v_in_pageSize*v_in_pageNow; ? v_sql:='select t2.* from (select t.*, rownum rn from (select * from ' || v_in_table || ') t where rownum <= ' || v_end_row || ') t2 where t2.rn >= '|| v_start_row; ? open v_out_result for v_sql; ? select count(*) into v_out_totalRows from emp; ? if mod(v_out_totalRows,v_in_pageSize)=0 then v_out_pageCount:=v_out_totalRows/v_in_pageSize; ? else ??? v_out_pageCount:=v_out_totalRows/v_in_pageSize+1; ? end if; end; / create or replace view employee_view as select * from employee; / create or replace view employee_view as select * from employee with read only; / create or replace trigger insert_trigger after insert on scott.employee begin ? dbms_output.put_line('添加了一條記錄'); end; / insert into employee values(110,'abcdefg','abcdefg123',to_date('2011-12-14 12:45:36','yyyy-mm-dd hh:mi:ss'),'abcdefg@126.com','China,toString'); create or replace trigger update_trigger after update on scott.employee for each row begin ? dbms_output.put_line('更改了一條數據'); end; / create or replace trigger before_brigger before delete on scott.employee begin ? if to_char(sysdate,'day') in ('星期日','星期六','星期四') then ??? raise_application_error('-20001','星期天不能刪除員工信息!'); ? end if; end; / create or replace trigger all_trigger before insert or update or delete on scott.employee begin ? case ??? when inserting then ????? dbms_output.put_line('請不要添加'); ????? raise_application_error(-20002,'不能添加數據'); ??? when updating then ????? dbms_output.put_line('請不要修改'); ????? raise_application_error(-20003,'不能修改數據'); ?? when deleting then ???? dbms_output.put_line('請不要刪除'); ???? raise_application_error(-20004,'不能刪除數據'); ? end case; end; / create or replace trigger new_old_trigger before update on scott.employee for each row begin ? if :new.id < :old.id then ??? dbms_output.put_line('ID不能變小'); ??? raise_application_error(-20005,'ID不能小于原來');? ? else ??? dbms_output.put_line('原來ID是 : ' || :old.id || '新的ID是 : ' || :new.id); ? end if; end; / create or replace trigger backup_trigger before delete on scott.employee for each row begin ? insert into employee_backup values (:old.id,:old.username); end; / create or replace trigger limit_trigger before update on scott.employee for each row begin ? if (:new.id<:old.id or :new.id>:old.id*2) then ??? dbms_output.put_line('ID范圍不對!'); ??? raise_application_error(-20006,'ID范圍不合理'); ? end if;??? end; / create or replace trigger limit_age_trigger before insert on scott.employee for each row begin ? if :new.id>200 then ??? dbms_output.put_line('ID過大'); ??? raise_application_error(-20007,'ID值太大了'); ? end if; end; / create or replace trigger limit_age_trigger before insert on scott.employee for each row begin ? if add_months(:new.birthday,18*12)>sysdate then ??? dbms_output.put_line('年齡太小了'); ??? raise_application_error(-20007,'對不起年齡太小了'); ? end if; end; / insert into employee values(120,'good','good123',to_date('1999-12-13 12:15:49','yyyy-mm-dd hh:mi:ss'),'good@126.com','China,Hubei'); create or replace trigger generate_birthday_trigger before insert on scott.test for each row declare ? v_length int; ? v_date varchar2(10); begin ? v_length := length(:new.IDCard); ? if v_length = 18 then ??? v_date := substr(:new.IDCard,7,8); ? elsif v_length = 15 then ??? v_date := '19' || substr(:new.IDCard,7,6); ? else ??? :new.birthday := null; ? end if; ? :new.birthday := to_date(v_date,'yyyy/mm/dd'); end; / create or replace procedure delete_all_procedure(v_ids in long) is v_sql long; begin ? v_sql:='delete from users t where t.id in (' || v_ids || ')'; ? execute immediate v_sql; end;

轉載于:https://www.cnblogs.com/dingyingsi/archive/2013/02/26/2933491.html

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