Jun 1, 2019 · A primary key is unique . A primary key is not null . Table has only one primary key. You are asking about the third condition. Well, ...

Nov 30, 2015 · I am doing an Sql assignment in which I need ... No, you can't have NULL's in primary keys!!! ... set to NOT NULL even if you specify it as nullable

May 5, 2012 · A PRIMARY KEY is a unique index where all key columns must be defined as NOT NULL . If they are not explicitly declared as NOT NULL , MySQL ...

Jul 29, 2016 · I came across this issue in Oracle 12g r 2. The desc MY_TABLE did not show the NOT NULL for a column that did have a NOT NULL constraint.

Sep 9, 2018 · Question 1: Since all main columns ( iso_code , iso_2_alpha , iso_3_alpha ) are NOT NULL and UNIQUE does make sense to create a composite ...

Hi Tom, One last reason why PRIMARY KEY should be used. Primary Key imposes UNIQUE CONSTRAINT as well. Thats not possible with UNIQUE INDEX and NOT NULL ...

Apr 12, 2020 · If necessary, make the PROJECT_ID column the primary key, that would implicitly not allow NULL values. Usually, the ID column in a table ...

Mar 7, 2020 · You must first describe what is your primary key in the table. I suspect that also the VERSION columns is corrupted by the invalid ETL (shouldn' ...