Execute INSERT multiple values if table is empty POSTGRES

Question

I am trying to add some default values in a postgres table. I can add one value but I want to add 5 default values. I’ve tried this below but it creates only one value since after inserting the first value the empty condition is no longer valid.

records_to_insert = [( 1,'foo', 30, 2, True),
                   ( 2,'bar', 60, 3, False),
                   ( 3,'hero', 95, 2, False),
                   ( 4,'borth', 45, 1, True),
                   ( 5,'here', 30, 2, True)]
sql_insert_query = """ INSERT INTO tester (id, name, time, rating,others)
                SELECT %s,%s,%s,%s,%s
                WHERE NOT EXISTS (SELECT * FROM tester) """
cursor = connection.cursor()
#executemany() to insert 3 rows
result  = cursor.executemany(sql_insert_query, records_to_insert)

I am using python3 and postgres10.5. I’ve also looked at this, this and this but no dice.

Asked By: fmakawa

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Source

Answer 1

Use psycopg2.extras.execute_values(cur, sql, argslist, template=None, page_size=100)

Execute a statement using VALUES with a sequence of parameters.
Parameters:

cur – the cursor to use to execute the query.

sql – the query to execute. It must contain a single %s placeholder, which will be replaced by a VALUES list. (…)

You should reformulate the query to use VALUES:

from psycopg2.extras import execute_values

sql_insert_query = """ 
    INSERT INTO tester (id, name, time, rating, others)
    SELECT * FROM (VALUES %s) s
    WHERE NOT EXISTS (SELECT 1 FROM tester) """
execute_values(cursor, sql_insert_query, records_to_insert)

Answered By: klin

Execute INSERT multiple values if table is empty POSTGRES

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