?? 15.txt
字號:
set transaction read only;
update emp
set ename = lower(ename);
select object_id
from all_objects
where rownum <= 2000;
drop table t;
create table t(
x int,
constraint ck_x_greater_than_zero check(x>0)
deferrable initially immediate
);
insert into t values(-1)
/
set constraint ck_x_greater_than_zero deferred;
insert into t values(-1);
commit
set constraint ck_x_greater_than_zero deferred;
insert into t values(-1);
set constraint ck_x_greater_than_zero immediate;
drop table t;
create table t(
x number(1)
);
insert into t values(1);
insert into t values(2);
rollback;
select * from t;
insert into t values(1);
insert into t values(2);
commit;
select * from t;
create table t(
x int,
constraint pk_t primary key(x)
);
create trigger t_trigger
after update
on t
for each row
begin
dbms_output.put_line('update x='||:old.x||' to x='||:new.x);
end;
/
insert into t values(1);
insert into t values(2);
set serveroutput on
begin
update t
set x = 2;
end;
/
set serveroutput on
begin
update t
set x = x + 1;
end;
/
create table parent(
pk int,
constraint pk_parent primary key(pk)
);
create table child(
fk int,
constraint fk_child foreign key(fk) references parent deferrable
);
insert into parent values(1);
insert into child values(1);
commit;
update parent
set pk = 2;
update child
set fk = 2;
set constraint fk_child deferred
/
update parent
set pk = 2;
select * from parent;
select * from child;
commit;
set constraint fk_child deferred;
update parent
set pk = 2;
select * from parent;
select * from child;
set constraint fk_child immediate;
update child
set fk = 2;
set constraint fk_child immediate;
commit;
select * from parent;
select * from child;
create table a
as
select 1 x
from dual;
create table b
as
select 1 x
from dual;
update a
set x=x+1;
update b
set x=x+1;
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