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Oracle PL/SQL/Constraints/Contraint Name - История изменений
2026-04-04T09:55:54Z
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в 13:45, 26 мая 2010
2010-05-26T13:45:19Z
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Admin: 1 версия
2010-05-26T10:02:01Z
<p>1 версия</p>
<p><b>Новая страница</b></p><div>==Add constraint to a column and give it a name==<br />
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<!-- start source code --><br />
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<source lang="sql"><br />
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SQL><br />
SQL> create table emp_1<br />
2 (emp_id number constraint pk_emp_id primary key,<br />
3 firstname varchar2(15) constraint firstname_nn not null,<br />
4 lastname varchar2(20) constraint lastname_nn not null,<br />
5 midinit char(1) );<br />
Table created.<br />
SQL><br />
SQL> drop table emp_1;<br />
Table dropped.<br />
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</source><br />
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==Name the constraint==<br />
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<!-- start source code --><br />
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<source lang="sql"><br />
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SQL> --name the constraint.<br />
SQL> -- creates a unique constraint on the columns a and b and names the constraint uq_myTable.<br />
SQL><br />
SQL> create table myTable (<br />
2 a number,<br />
3 b number,<br />
4 c number,<br />
5 constraint uq_myTable unique (a,b)<br />
6 );<br />
Table created.<br />
SQL><br />
SQL><br />
SQL> insert into myTable values (4, 3, 5);<br />
1 row created.<br />
SQL> insert into myTable values (4, 1, 5);<br />
1 row created.<br />
SQL> insert into myTable values (4, 2, 5);<br />
1 row created.<br />
SQL> insert into myTable values (4, 3, 5);<br />
insert into myTable values (4, 3, 5)<br />
*<br />
ERROR at line 1:<br />
ORA-00001: unique constraint (SYS.UQ_MYTABLE) violated<br />
<br />
SQL><br />
SQL> select * from myTable;<br />
A B C<br />
---------- ---------- ----------<br />
4 3 5<br />
4 1 5<br />
4 2 5<br />
SQL><br />
SQL> drop table myTable;<br />
Table dropped.<br />
SQL><br />
SQL><br />
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</source><br />
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==SYS.SYS_C004353 is the contraint name==<br />
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<!-- start source code --><br />
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<source lang="sql"><br />
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SQL> --Unique Key<br />
SQL><br />
SQL><br />
SQL> create table myTable (<br />
2 a number unique,<br />
3 b number<br />
4 );<br />
Table created.<br />
SQL><br />
SQL> desc myTable;<br />
Name Null? Type<br />
----------------------------------------------------------------------------------------------------- -------- --------------------------------------------------------------------<br />
A NUMBER<br />
B NUMBER<br />
SQL><br />
SQL> -- if a column is not explicitely defined as not null, nulls can be inserted multiple times:<br />
SQL><br />
SQL> insert into myTable values (4, 5);<br />
1 row created.<br />
SQL> insert into myTable values (4, 1);<br />
insert into myTable values (4, 1)<br />
*<br />
ERROR at line 1:<br />
ORA-00001: unique constraint (SYS.SYS_C004353) violated<br />
<br />
SQL> insert into myTable values (9, 8);<br />
1 row created.<br />
SQL> insert into myTable values (6, 9);<br />
1 row created.<br />
SQL> insert into myTable values (null,9);<br />
1 row created.<br />
SQL> insert into myTable values (null,9);<br />
1 row created.<br />
SQL><br />
SQL> select * from myTable;<br />
A B<br />
---------- ----------<br />
4 5<br />
9 8<br />
6 9<br />
9<br />
9<br />
SQL><br />
SQL> drop table myTable;<br />
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</source></div>
Admin