Write a postgre SQL statement to create a table named countries, including country_id, country_name and region_id and make sure that no duplicate data against column country_id will be allowed at the time of insertion
- Postgre SQL
- 2021-09-28
- mhanasmh00489829403
الأجوبة
CREATE TABLE IF NOT EXISTS countries (
COUNTRY_ID varchar(2) NOT NULL,
COUNTRY_NAME varchar(40) NOT NULL,
REGION_ID decimal(10,0) NOT NULL,
UNIQUE(COUNTRY_ID)
);This example can also be written like below.
Code:
CREATE TABLE IF NOT EXISTS countries (
COUNTRY_ID varchar(2) NOT NULL UNIQUE,
COUNTRY_NAME varchar(40) NOT NULL,
REGION_ID decimal(10,0) NOT NULL
);Output:
postgres=# CREATE TABLE IF NOT EXISTS countries ( postgres(# COUNTRY_ID varchar(2) NOT NULL, postgres(# COUNTRY_NAME varchar(40) NOT NULL, postgres(# REGION_ID decimal(10,0) NOT NULL, postgres(# UNIQUE(COUNTRY_ID) postgres(# ); CREATE TABLE
Here is the command to see the structure of the table :
postgres=# \d countries
Table "public.countries"
Column | Type | Modifiers
--------------+-----------------------+-----------
country_id | character varying(2) | not null
country_name | character varying(40) | not null
region_id | numeric(10,0) | not null
Indexes:
"countries_country_id_key" UNIQUE CONSTRAINT, btree (country_id)
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