Tag: create-table

How to avoid adding duplicate foreign key constraints

alter-table create-table foreign-keys mysql sql

I would to know if it is possible to avoid adding several times the same foreign key constraint? Example: if I execute 3 times the query below, the constraint will exist with 3 times in phpmyadmin… It would be great that it would be rejected the second and third time I apply that query. Answer You can g…

column “parent_id” referenced in foreign key constraint does not exist when creating SQL table

create-table postgresql sql

I am new in SQL and trying to understand Foreign key syntax. I know this was asked in multiple questions but each question I found did not seem to teach me what I am doing wrong here. This is my SQL code: And this is the error I am getting: Answer You need to add fields in your tables to

PostgreSQL: Create table if not exists AS

create-table postgresql sql

I’m using PostgreSQL and am an SQL beginner. I’m trying to create a table from a query, and if I run: CREATE TABLE table_name AS (….query…) it works just fine. But then if I add ‘if not …