Oracle 10g primary key latency

 

-- Create Table try as select * from student basic information; -- add the deferred primary key alter table try add constraint pk_try primary key (student ID) deferrable initially immediate; -- set the primary key delay set constraint pk_try deferred; -- Insert rows with duplicate primary keys

-- Create a table Create Table try as select * from student basic information; -- Add a delayed primary key Alter table try add constraint pk_try primary key (student ID) deferrable initially immediate; -- Set primary key latency Set constraint pk_try deferred; -- Insert rows with duplicate primary keys Insert into try values ('20170101', 'zhang san', 'mal', 'Han nationality '); -- Delete a dependency with a foreign keyPrimary Key Alter table student basic information drop constraint pk_baseinfo cascade; -- Add back Alter table student basic information add constraint pk_baseinfo primary key (student ID ); -- AddDelayedForeign key Alter table Student Score add constraint fk_info_grade foreign key (student ID) References student basic information (student ID) deferrable initially immediate; -- Set the foreign key latency Set constraint fk_info_grade deferred; -- The insert operation does not meet the foreign key requirements.ConstraintsRows Insert into student Score values ('2017010', 'c010', 80 ); -- EnableConstraintsInvalid Alter table Student Score disable constraint fk_info_grade; -- Insert again Insert into student Score values ('2017010', 'c010', 80 ); -- EnableConstraintsEffective Alter table Student Score enable constraint fk_info_grade; -- Delete a column Delete from student achievement where student ID = '000000 '; -- Create a student renewal table Create Table try2 as select * from Student Score; -- Add a foreign key for cascading Deletion Alter table try2 add constraint fk_try2 foreign key (student ID) References try (student ID) on Delete cascade; -- Delete the last record in try Delete from try where student ID = '123 '; -- Run StorageConstraintsLine System script @ D: \ oracle \ product \ 10.2.0 \ db_1 \ RDBMS \ admin \ utlexcpt. SQL -- Search for ViolationConstraintsCondition row Create Table student as select * from student basic information; Alter table student add constraint pk_student primary key (student ID ); Alter table student disable constraint pk_student; Insert into student values ('20140901', 'zhang san', 'male', 'Han nationality '); Alter table student enable constraint pk_student; Alter table student enable constraint pk_student exceptions into exceptions; Select * from exceptions; Select * from student where rowid = 'aaam7saaeaaaaccabl' Alter table Student Score disable constraint fk_info_grade; Insert into student Score values ('20170101', 'c011', 80 ); Commit; Alter table student scores enable constraint fk_info_grade exceptions into exceptions; Select * from exceptions; 5. Host md d: \ oracle \ ext_file Host Copy D: \ oracle \ student.txt D: \ oracle \ ext_file \*.* Create or replace directory stud_ext as 'd: \ oracle \ ext_file '; Conn sys/AAA as sysdba Grant read on directory stud_ext to Hu; Conn Hu/AAA Create Table student_ext (SNO varchar2 (20 ), Name varchar2 (8 ), Sex varchar2 (2 ), Nation varchar2 (8 )) Organization external ( Type oracle_loader Default directory stud_ext Access parameters (fields terminated ',') Location('student.txt ') ) Reject limit Unlimited

 

 

Initially released by wabjtam123
[B] ALTER TABLE employee add constraint pk_employee_empno primary key (empno) deferrable initally immediate;

This indicatesYesYesDelayed primary key constraint

Heard of this delayYesIndicates that the check is performed after the transaction is committed, and the check is not performed after the transaction is committed without delay. For example, if an update is inserted, the check is performed immediately if the transaction is not committed.

I think there is a latency constraint.WhatMeaning: I don't feel any meaning at all. Instead, the function is used to harm people. If I have done more than N tasks, I will submit the tasks again. When I submit the tasks, I will make all the previous tasks in vain, it's better to remind me early that I can't do this. I have constraints. What do you think? [/B]

If youYesIt is useful to input data in form mode. If there is no delay, the input order must be strictly defined because foreign key connections have been established in several tables, otherwise, an error that violates integrity constraints will occur.