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Oracle PL/SQL/Constraints/Defer Constraint - История изменений
2026-05-25T18:28:50Z
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в 13:45, 26 мая 2010
2010-05-26T13:45:19Z
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Admin: 1 версия
2010-05-26T10:02:00Z
<p>1 версия</p>
<p><b>Новая страница</b></p><div>==Deferrable initially immediate==<br />
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<!-- start source code --><br />
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<source lang="sql"><br />
<br />
SQL> create table t( x int,<br />
2 constraint x_greater_than_zero check ( x > 0 )<br />
3 deferrable initially immediate<br />
4 )<br />
5 /<br />
<br />
SQL> insert into t values ( -1 );<br />
insert into t values ( -1 )<br />
*<br />
ERROR at line 1:<br />
ORA-02290: check constraint (sqle.X_GREATER_THAN_ZERO) violated<br />
<br />
SQL><br />
SQL> select * from t;<br />
no rows selected<br />
SQL><br />
SQL><br />
SQL> set constraint x_greater_than_zero deferred;<br />
Constraint set.<br />
SQL><br />
SQL> insert into t values ( -1 );<br />
1 row created.<br />
SQL><br />
SQL><br />
SQL> select * from t;<br />
X<br />
----------<br />
-1<br />
SQL><br />
SQL> set constraint x_greater_than_zero deferred;<br />
Constraint set.<br />
SQL><br />
SQL> insert into t values ( -1 );<br />
1 row created.<br />
SQL><br />
SQL> select * from t;<br />
X<br />
----------<br />
-1<br />
-1<br />
SQL><br />
SQL> set constraint x_greater_than_zero immediate;<br />
set constraint x_greater_than_zero immediate<br />
*<br />
ERROR at line 1:<br />
ORA-02290: check constraint (sqle.X_GREATER_THAN_ZERO) violated<br />
<br />
SQL><br />
SQL> drop table t;<br />
drop table t<br />
*<br />
ERROR at line 1:<br />
ORA-02091: transaction rolled back<br />
ORA-02290: check constraint (sqle.X_GREATER_THAN_ZERO) violated<br />
<br />
SQL><br />
SQL><br />
<br />
</source><br />
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==Deferring Constraint Checking: check constraint when "commit"==<br />
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<br />
<!-- start source code --><br />
<br />
<source lang="sql"><br />
<br />
SQL><br />
SQL> -- Deferring Constraint Checking: check constraint when "commit"<br />
SQL><br />
SQL> CREATE TABLE chicken(chicken_ID INT PRIMARY KEY, egg_ID INT);<br />
Table created.<br />
SQL><br />
SQL> CREATE TABLE egg(egg_ID INT PRIMARY KEY, chicken_ID INT);<br />
Table created.<br />
SQL><br />
SQL><br />
SQL> ALTER TABLE chicken ADD CONSTRAINT chickenREFegg<br />
2 FOREIGN KEY (egg_ID) REFERENCES egg(egg_ID)<br />
3 INITIALLY DEFERRED DEFERRABLE;<br />
Table altered.<br />
SQL><br />
SQL> ALTER TABLE egg ADD CONSTRAINT eggREFchicken<br />
2 FOREIGN KEY (chicken_ID) REFERENCES chicken(chicken_ID)<br />
3 INITIALLY DEFERRED DEFERRABLE;<br />
Table altered.<br />
SQL><br />
SQL><br />
SQL> INSERT INTO chicken VALUES(1, 2);<br />
1 row created.<br />
SQL> INSERT INTO egg VALUES(2, 1);<br />
1 row created.<br />
SQL><br />
SQL> COMMIT;<br />
Commit complete.<br />
SQL><br />
SQL> select * from chicken;<br />
CHICKEN_ID EGG_ID<br />
---------- ----------<br />
1 2<br />
SQL> select * from egg;<br />
EGG_ID CHICKEN_ID<br />
---------- ----------<br />
2 1<br />
SQL><br />
SQL> drop table chicken cascade constraint;<br />
Table dropped.<br />
SQL> drop table egg cascade constraint;<br />
Table dropped.<br />
SQL><br />
SQL><br />
<br />
</source></div>
Admin