plsql的异常处理部分学习整理
ORACLE的PLSQL编程,异常处理主要分为3大块
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AORACLE系统预定义异常 ,比如NO_DATA_FOUND;
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B非预定义异常 ,用PRAGMA定义
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C自定义异常
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下面是主要的测试脚本
--除数为零的异常处理(预定义异常)set serveroutput on;declare v_dividend number:=50; v_divisor number:=0; v_quotient number; begin v_quotient:=v_dividend/v_divisor; exception when ZERO_DIVIDE THEN dbms_output.put_line('除数为零'); end; / --no_data_foud异常(预定义异常)select * from students;declarev_id students.student_id%type;v_sname students.name%type;begin v_id:=&student_id; select name into v_sname from students where student_id=v_id; dbms_output.put_line('学生姓名'||v_sname); exception when no_data_found then dbms_output.put_line('输入的学号不存在');end;--too_many_rows 异常(预定义异常)declarev_SPECIALTY students.SPECIALTY%type;v_sname students.name%type;begin v_SPECIALTY:='&specialty'; select name into v_sname from students where SPECIALTY=v_SPECIALTY; dbms_output.put_line('学生姓名'||v_sname); exception when too_many_rows then dbms_output.put_line('返回的学生记录多于一行');end;--考虑两种系统预定义异常 too_many_rows 和no_data_found异常(预定义异常)declarev_SPECIALTY students.SPECIALTY%type;v_sname students.name%type;begin v_SPECIALTY:='&specialty'; --这里的加引号和上面的不加引号有什么不一样? select name into v_sname from students where SPECIALTY=v_SPECIALTY; dbms_output.put_line('学生姓名'||v_sname); exception when too_many_rows then dbms_output.put_line('返回的学生记录多于一行'); when no_data_found then dbms_output.put_line('没有记录');end;--非预定义异常 e_deptid EXCEPTION;(删除有主外键约束的表的异常处理)--pragma EXCEPTION_INIT(e_deptid ,-2292);select * from departments;set serveroutput on;declaree_deptid EXCEPTION;pragma EXCEPTION_INIT(e_deptid ,-2292);begindelete from departments where department_id=101;exceptionwhen e_deptid thendbms_output.put_line('在教师表中存在子记录'); --参照完整性异常,看似不会产生异常,但是假如于其他表有主外键关联则会出异常end;--插入有主外键约束的表的处理select * from teachers;set serveroutput on;declaree_deptid EXCEPTION;pragma EXCEPTION_INIT(e_deptid ,-2292);begininsert into teachers values (11101,'王彤','教授','01-9月-1990',1000,3000,999);exceptionwhen e_deptid thendbms_output.put_line('插入记录的部门号在父表中不存在'); --参照完整性异常,看似不会产生异常,但是假如于其他表有主外键关联则会出异常end;---插入的记录已经存在异常select * from students;set serveroutput on;declaree_studentid EXCEPTION;pragma EXCEPTION_INIT(e_studentid ,-0001);begininsert into students values (10205,null,'王三','男','26-12月-1989','自动化');exceptionwhen e_studentid thendbms_output.put_line('插入记录已经存在---'||SQLCODE||'错误描述---'||SQLERRM); --参照完整性异常,看似不会产生异常,但是假如于其他表有主外键关联则会出异常end;--自定义异常declaree_wage EXCEPTION;v_wage teachers.wage%type;beginv_wage:=&wage;insert into teachers values (10111,'王彤','教授','01-9月-1990',1000,v_wage,101);if v_wage <0 then raise e_wage;end if;exception when e_wage thendbms_output.put_line('教师工资不能为负');rollback;when others thendbms_output.put_line('未知异常');end;/?