Postgres how can I make 2 columns unique

Question

Hello I am new to postgres and know how to make a column unique however I need to make 2 pairs of columns unique (City,State). I have a table where people insert data different cities and states and I would like to make that pair unique. For Example: Dallas,Texas Houston,Texas Dallas,Texas : This should cause an error or not be allowed because the pair of (Dallas,Texas) is not unique. I am using postgres 9.4 and pgadmin any suggestions would be great

http://stackoverflow.com/questions/1194438/can-i-add-a-unique-constraint-to-a-postgresql-table-after-its-already-created — Pரதீப், Sep 24 '15 at 15:14

score 5 · Accepted Answer · answered Sep 24 '15 at 15:13

5

You can create a unique index on the pair:

create unique index idx_table_city_state on table(city, state);

You can also use a unique constraint in the table definition.

answered Sep 24 '15 at 15:13

Gordon Linoff

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Postgres how can I make 2 columns unique

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