Primary key with check option : Primary Key « Constraints « PostgreSQL






  1. PostgreSQL
  2. Constraints
  3. Primary Key

Primary key with check option


postgres=#
postgres=# CREATE TABLE employee
postgres-#              (id integer PRIMARY KEY CHECK (id > 100),
postgres(#               last_name text NOT NULL,
postgres(#               first_name text);
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "employee_pkey" for table "employee"
CREATE TABLE
postgres=#
postgres=# insert into employee values(1000, 'a', 'b');
INSERT 0 1
postgres=# insert into employee values(200,  'c',  'd');
INSERT 0 1
postgres=# insert into employee values(11,   'a',   'b');
ERROR:  new row for relation "employee" violates check constraint "employee_id_check"
postgres=#
postgres=# select * from employee;
  id  | last_name | first_name
------+-----------+------------
 1000 | a         | b
  200 | c         | d
(2 rows)

postgres=#
postgres=# drop table employee;
DROP TABLE
postgres=#








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3.Indicate one column as the primary key column
4.PRIMARY KEY will create implicit index
5.Add PRIMARY KEY in table creation
6.Use sequence value as a primary key