Oracle扩展PL/SQL简介(五)

7. 异常处理

exception

when <exception_expression> then

…

when <exception_expression> then

…

end;

查询预定义异常，可以得知自定义异常方法

select text from dba_source where name='STANDARD' and text like '%EXCEPTION_INIT%';

TEXT

----------------------------------------------------------------

pragma EXCEPTION_INIT(CURSOR_ALREADY_OPEN, '-6511');

pragma EXCEPTION_INIT(DUP_VAL_ON_INDEX, '-0001');

pragma EXCEPTION_INIT(TIMEOUT_ON_RESOURCE, '-0051');

pragma EXCEPTION_INIT(INVALID_CURSOR, '-1001');

pragma EXCEPTION_INIT(NOT_LOGGED_ON, '-1012');

pragma EXCEPTION_INIT(LOGIN_DENIED, '-1017');

pragma EXCEPTION_INIT(NO_DATA_FOUND, 100);

pragma EXCEPTION_INIT(ZERO_DIVIDE, '-1476');

pragma EXCEPTION_INIT(INVALID_NUMBER, '-1722');

pragma EXCEPTION_INIT(TOO_MANY_ROWS, '-1422');

pragma EXCEPTION_INIT(STORAGE_ERROR, '-6500');

pragma EXCEPTION_INIT(PROGRAM_ERROR, '-6501');

pragma EXCEPTION_INIT(VALUE_ERROR, '-6502');

pragma EXCEPTION_INIT(ACCESS_INTO_NULL, '-6530');

pragma EXCEPTION_INIT(COLLECTION_IS_NULL , '-6531');

pragma EXCEPTION_INIT(SUBSCRIPT_OUTSIDE_LIMIT,'-6532');

pragma EXCEPTION_INIT(SUBSCRIPT_BEYOND_COUNT ,'-6533');

pragma EXCEPTION_INIT(ROWTYPE_MISMATCH, '-6504');

PRAGMA EXCEPTION_INIT(SYS_INVALID_ROWID, '-1410');

pragma EXCEPTION_INIT(SELF_IS_NULL, '-30625');

pragma EXCEPTION_INIT(CASE_NOT_FOUND, '-6592');

pragma EXCEPTION_INIT(USERENV_COMMITSCN_ERROR, '-1725');

pragma EXCEPTION_INIT(NO_DATA_NEEDED, '-6548');

pragma EXCEPTION_INIT(INVALID_USERENV_PARAMETER, -2003);

pragma EXCEPTION_INIT(ICD_UNABLE_TO_COMPUTE, -6594);

25 rows selected.

处理预定义异常，这些是oracle预先定义好的异常

declare

v_dept departments%rowtype;

begin

v_dept.department_id:=100;

v_dept.department_name:='HR';

insert into departments(department_id, department_name)

values(v_dept.department_id, v_dept.department_name);

exception

when DUP_VAL_ON_INDEX then

dbms_output.put_line(SQLERRM); --打印错误码

end;

/

ORA-00001: unique constraint (HR.DEPT_ID_PK) violated

处理非预定义异常

declare

Invalid_column_name exception; --定义异常

pragma exception_init(Invalid_column_name,-904); --绑定异常码

v_update_text varchar2(100):='update employees set EMAILS= "abc@def.com" where EMPLOYEE_ID= 181';

begin

execute immediate v_update_text;

exception

when Invalid_column_name then

dbms_output.put_line('invalid column name! ');

end;

/

invalid column name!

自定义异常码

declare

USER_ERROR exception; --定义异常

pragma exception_init(USER_ERROR,-20001); --分配异常码，自定义异常码是20000以后的数字

begin

dbms_output.put_line('自定义异常码：'||'-20001 ');

raise USER_ERROR;

exception

when USER_ERROR then

dbms_output.put_line('不能修改员工工资！');

end;

/

作用域和可视性：

begin

declare

nested_excp exception;

begin

raise nested_excp;

end;

exception

when nested_excp then --这里会出错，非nested_excp定义的作用域

dbms_output.put_line(' nested_excp ');

end;

/

一般最后捕获异常方法when others then

declare

nested_excp exception;

begin

raise nested_excp;

exception

when others then

dbms_output.put_line(' nested_excp--');

dbms_output.put_line(sqlcode || ' is ' || sqlerrm);

raise; --再次把异常抛出

end;

/

declare

v_dept departments%rowtype;

begin

v_dept.department_id:=100;

v_dept.department_name:='HR';

insert into departments(department_id, department_name)

values(v_dept.department_id, v_dept.department_name);

exception

when others then

dbms_output.put_line('最后的捕获异常，所有剩下的异常都捕获！');

end;

/

捕获异常代码和错误描述(SQLCODE SQLERRM)

前面代码已经有所使用：

declare

v_dept departments%rowtype;

begin

v_dept.department_id:=100;

v_dept.department_name:='HR';

insert into departments(department_id, department_name)

values(v_dept.department_id, v_dept.department_name);

Exception

When others then

dbms_output.put_line(sqlcode || ' is ' || sqlerrm);

end;

/

-1 is ORA-00001: unique constraint (HR.DEPT_ID_PK) violated