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Oracle PL/SQL/Constraints/DELETE SET NULL - История изменений
2026-04-04T10:08:16Z
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в 13:45, 26 мая 2010
2010-05-26T13:45:19Z
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http://www.sqle.ru/index.php?title=Oracle_PL/SQL/Constraints/DELETE_SET_NULL&diff=2577&oldid=prev
Admin: 1 версия
2010-05-26T10:02:01Z
<p>1 версия</p>
<p><b>Новая страница</b></p><div>==Create a foreign key "set null on delete" with more than one field==<br />
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<!-- start source code --><br />
<br />
<source lang="sql"><br />
<br />
SQL><br />
SQL><br />
SQL><br />
SQL> -- Create a foreign key "set null on delete" with more than one field<br />
SQL><br />
SQL> CREATE TABLE supplier<br />
2 ( supplier_id numeric(10) not null,<br />
3 supplier_name varchar2(50) not null,<br />
4 contact_name varchar2(50),<br />
5 CONSTRAINT supplier_pk PRIMARY KEY (supplier_id, supplier_name)<br />
6 );<br />
Table created.<br />
SQL><br />
SQL><br />
SQL> CREATE TABLE products<br />
2 ( product_id numeric(10) not null,<br />
3 supplier_id numeric(10),<br />
4 supplier_name varchar2(50),<br />
5 CONSTRAINT fk_supplier_comp<br />
6 FOREIGN KEY (supplier_id, supplier_name)<br />
7 REFERENCES supplier(supplier_id, supplier_name)<br />
8 ON DELETE SET NULL<br />
9 );<br />
Table created.<br />
SQL><br />
SQL><br />
SQL> desc products;<br />
Name Null? Type<br />
----------------------------------------------------------------------------------------------------- -------- --------------------------------------------------------------------<br />
PRODUCT_ID NOT NULL NUMBER(10)<br />
SUPPLIER_ID NUMBER(10)<br />
SUPPLIER_NAME VARCHAR2(50)<br />
SQL> desc supplier;<br />
Name Null? Type<br />
----------------------------------------------------------------------------------------------------- -------- --------------------------------------------------------------------<br />
SUPPLIER_ID NOT NULL NUMBER(10)<br />
SUPPLIER_NAME NOT NULL VARCHAR2(50)<br />
CONTACT_NAME VARCHAR2(50)<br />
SQL><br />
SQL> drop table products cascade constraints;<br />
Table dropped.<br />
SQL><br />
SQL> drop table supplier cascade constraints;<br />
Table dropped.<br />
SQL><br />
SQL><br />
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</source><br />
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==Foreign Keys with "set null on delete"==<br />
<br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="sql"><br />
<br />
SQL><br />
SQL> -- Foreign Keys with "set null on delete"<br />
SQL><br />
SQL> CREATE TABLE supplier<br />
2 ( supplier_id numeric(10) not null,<br />
3 supplier_name varchar2(50) not null,<br />
4 contact_name varchar2(50),<br />
5 CONSTRAINT supplier_pk PRIMARY KEY (supplier_id)<br />
6 );<br />
Table created.<br />
SQL><br />
SQL><br />
SQL> CREATE TABLE products<br />
2 ( product_id numeric(10) not null,<br />
3 supplier_id numeric(10),<br />
4 CONSTRAINT fk_supplier<br />
5 FOREIGN KEY (supplier_id)<br />
6 REFERENCES supplier(supplier_id)<br />
7 ON DELETE SET NULL<br />
8 );<br />
Table created.<br />
SQL><br />
SQL> desc products;<br />
Name Null? Type<br />
----------------------------------------------------------------------------------------------------- -------- --------------------------------------------------------------------<br />
PRODUCT_ID NOT NULL NUMBER(10)<br />
SUPPLIER_ID NUMBER(10)<br />
SQL> desc supplier;<br />
Name Null? Type<br />
----------------------------------------------------------------------------------------------------- -------- --------------------------------------------------------------------<br />
SUPPLIER_ID NOT NULL NUMBER(10)<br />
SUPPLIER_NAME NOT NULL VARCHAR2(50)<br />
CONTACT_NAME VARCHAR2(50)<br />
SQL><br />
SQL> drop table products cascade constraints;<br />
Table dropped.<br />
SQL><br />
SQL> drop table supplier cascade constraints;<br />
Table dropped.<br />
SQL><br />
SQL><br />
<br />
</source></div>
Admin