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https://www.postgresqltutorial.com › postgresql-tutorial › postgresql-primary-key
PostgreSQL Primary KeyLearn how to create, add, drop and modify primary key constraints in PostgreSQL tables. A primary key is a column or a group of columns that uniquely identifies a row in a table.
https://www.postgresql.org › docs › current › ddl-constraints.html
PostgreSQL: Documentation: 17: 5.5. ConstraintsAdding a primary key will automatically create a unique B-tree index on the column or group of columns listed in the primary key, and will force the column(s) to be marked NOT NULL. A table can have at most one primary key.
https://www.geeksforgeeks.org › postgresql-primary-key
PostgreSQL - Primary Key - GeeksforGeeksPostgreSQL – Primary Key. A primary key is a column or a group of columns used to uniquely identify a row in a table. Technically, a primary key constraint combines a NOT NULL constraint and a UNIQUE constraint. Each table can only have one primary key.
https://stackoverflow.com › questions › 23533184
Primary key for multiple columns in PostgreSQL?There can only be one PRIMARY KEY constraint per table (spanning one or more columns) - as indicated by the word "primary". You can have additional UNIQUE constraints (spanning one or more columns). Short syntax with "column constraints": sl_no int PRIMARY KEY -- NOT NULL due to PK.
https://www.postgresql.org › docs › current › sql-createtable.htm
PostgreSQL: Documentation: 17: CREATE TABLEThe PRIMARY KEY constraint specifies that a column or columns of a table can contain only unique (non-duplicate), nonnull values. Only one primary key can be specified for a table, whether as a column constraint or a table constraint.
https://blog.devart.com › postgresql-primary-key.html
PostgreSQL Primary Key - A Complete Guide [2024] - Devart BlogLearn how to use primary keys in PostgreSQL to ensure referential integrity and uniqueness of data. See examples of creating, altering, dropping, and changing primary keys using CREATE TABLE, ALTER TABLE, and other commands.
https://www.postgresql.org › docs › current › indexes-unique.html
PostgreSQL: Documentation: 17: 11.6. Unique IndexesPostgreSQL automatically creates a unique index when a unique constraint or primary key is defined for a table. The index covers the columns that make up the primary key or unique constraint (a multicolumn index, if appropriate), and is the mechanism that enforces the constraint.
https://www.techonthenet.com › postgresql › primary_keys.php
PostgreSQL: Primary Keys - TechOnTheNetThis PostgreSQL tutorial explains how to create, drop, disable, and enable a primary key in PostgreSQL with syntax and examples.
https://docs.postgresql.fr › 12 › ddl-constraints.html
5.4. Contraintes - PostgreSQLCREATE TABLE commandes ( id_commande integer PRIMARY KEY, no_produit integer REFERENCES produits, quantite integer ); parce qu'en l'absence de liste de colonnes, la clé primaire de la table de référence est utilisée comme colonne de référence.
https://www.tutorialsteacher.com › postgresql › primary-key
Primary Key in PostgreSQL - TutorialsTeacher.comIn PostgreSQL, you can define a primary key on a single column by writing "primary key" after the column name in the CREATE TABLE statement. For example, the following CREATE TABLE statement will create the employee table with a primary key defined on emp_id column.
