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PostgreSQL - make column values unique

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Created by:

Tehya-Blanchard

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In this article, we would like to show you how to make column values unique in PostgreSQL.

Quick solution:

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ALTER TABLE "table_name" 
ADD UNIQUE ("column_name");

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ALTER TABLE "table_name"
ADD CONSTRAINT "constraing_name" UNIQUE ("column1", "column2", "columnN");

Practical example

Edit

To show how to make column values unique, we will use the following table:

PostgreSQL - example data used to make column values unique

Example 1 - make single column unique

Edit

In this example, we will make name column unique.

Query:

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ALTER TABLE "users"
ADD CONSTRAINT "UC_username" UNIQUE ("name");

Result:

Using query

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SHOW INDEXES FROM "users";

PostgreSQL - make column value unique - result

Using HeidiSQL

Example 2 - make multiple columns unique

Edit

In this example, we will make name and country columns unique.

Query:

xxxxxxxxxx
 
ALTER TABLE "users"
ADD CONSTRAINT "UC_user" UNIQUE ("name", "country");

Result:

Using query

xxxxxxxxxx
 
SHOW INDEXES FROM "users";

PostgreSQL - make multiple column values unique - result

Using HeidiSQL:

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