PostgreSQL Insert Record: Insert rows into the table to ensure that the value of the key column will be unique and auto incremented
9. Write a SQL statement to insert rows into the table countries in which the value of country_id column will be unique and auto incremented.
Sample Solution:
Code:
Here is the code to create a sample table countries:
CREATE TABLE countries (
COUNTRY_ID SERIAL PRIMARY KEY,
COUNTRY_NAME varchar(40) NOT NULL,
REGION_ID integer NOT NULL
);
Now insert one record into the table:
INSERT INTO countries(COUNTRY_NAME,REGION_ID) VALUES('India',185);
Here is the command to see the list of inserting rows:
postgres=# SELECT * FROM countries; country_id | country_name | region_id ------------+--------------+----------- 1 | India | 185 (1 row)
Now insert another record into the table :
INSERT INTO countries(COUNTRY_NAME,REGION_ID) VALUES('Japan',102);
Now see the value of the key field incremented automatically :
postgres=# SELECT * FROM countries; country_id | country_name | region_id ------------+--------------+----------- 1 | India | 185 2 | Japan | 102 (2 rows)
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Previous: Write a SQL statement to insert a record into the table countries to ensure that, at country_id and the region_id combination will be entered once in the table.
Next: Write a SQL statement to insert records into the table countries to ensure that the country_id column will not contain any duplicate data and this will be automatically incremented and the column country_name will be filled up by 'N/A' if no value assigned to that column.
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