How to put constraint??

Question

hi,
1st case
i have a table ABC , in this i have 3 columns col1 col2 col3
now i want to put constraint on table level that col1 n col2 always b unique together like
col1 col2 col3
100 1 item
100 2 item
100 3 item
200 1 item
200 2 item
2nd case
i have a table XYZ contains columns col1 col2 col3.. here i want col3 should be unique as per col1 and col2 like
col1 col2 col3
100 1 10
100 1 11
100 1 12
100 1 13
100 1 14
i know that unique can b possible in for every column individually but considering more than one column dont know...
please tell how to resolve??
thanks

Answer 1

Hi FRNzzz!! wrote:
2nd case
i have a table XYZ contains columns col1 col2 col3.. here i want col3 should be unique as per col1 and col2 like
col1 col2 col3
100 1 10
100 1 11
100 1 12
100 1 13
100 1 14
Create a unique constraint on (col1, col2, col3).
test@ORA11G>
test@ORA11G> --
test@ORA11G> create table xyz (col1 number, col2 number, col3 number);
Table created.
test@ORA11G> alter table xyz add constraint xyz_u1 unique (col1, col2, col3);
Table altered.
test@ORA11G> --
test@ORA11G> insert into xyz (col1, col2, col3) values (100, 1, 10);
1 row created.
test@ORA11G>
test@ORA11G> -- try inserting a repetition of col3 for the same combination of (col1, col2)
test@ORA11G> insert into xyz (col1, col2, col3) values (100, 1, 10);
insert into xyz (col1, col2, col3) values (100, 1, 10)
ERROR at line 1:
ORA-00001: unique constraint (TEST.XYZ_U1) violated
test@ORA11G>
test@ORA11G> -- doesn't work !
test@ORA11G> -- now try with a different value of col3; col1 and col2 remaining the same
test@ORA11G> insert into xyz (col1, col2, col3) values (100, 1, 11);
1 row created.
test@ORA11G>
test@ORA11G> -- works now
test@ORA11G>isotope