PostgreSQL Create Table: Create a table countries, with columns country_id, country_name and region_id

1. Write a SQL statement to create a simple table countries, including columns country_id, country_name and region_id.

Sample Solution:

Code:

-- This SQL statement creates a new table called 'countries' with specified columns.

CREATE TABLE countries (
    COUNTRY_ID varchar(3), -- Defines a column 'COUNTRY_ID' to store country IDs as strings with a maximum length of 3 characters.
    COUNTRY_NAME varchar(45), -- Defines a column 'COUNTRY_NAME' to store country names as strings with a maximum length of 45 characters.
    REGION_ID decimal(10,0) -- Defines a column 'REGION_ID' to store region IDs as decimal numbers with a precision of 10 digits and no decimal places.
);

Explanation:

• The CREATE TABLE statement is used to create a new table in the database.
• The table is named ''countries'.
• Inside the parentheses, each line specifies a column in the table along with its data type and optional constraints.
• varchar(3) indicates a variable-length character string with a maximum length of 3 characters for the 'COUNTRY_ID' column.
• varchar(45) indicates a variable-length character string with a maximum length of 45 characters for the 'COUNTRY_NAME' column.
• decimal(10,0) indicates a decimal number with a precision of 10 digits and no decimal places for the 'REGION_ID' column.
• Each column definition is separated by a comma.

Output:

postgres=# CREATE TABLE countries (
postgres(# COUNTRY_ID varchar(3),
postgres(# COUNTRY_NAME varchar(45),
postgres(# REGION_ID decimal(10,0)
postgres(# );
CREATE TABLE

To see the structure of the created table :

postgres=# postgres=# \d countries;
           Table "public.countries"
    Column    |         Type          | Modifiers
--------------+-----------------------+-----------
 country_id   | character varying(3)  |
 country_name | character varying(45) |
 region_id    | numeric(10,0)         |

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Next: Write a SQL statement to create a simple table countries, including columns country_id,country_name and region_id which already exist.