Cannot insert the value NULL into column ‘ExampleID’

Upon executing I keep receiving the error:

Cannot insert the value NULL into column ‘ExampleID’, table ‘DB_Example.dbo.tbl_Example’; column does not allow nulls. INSERT fails.

However I don’t think any NULL values are present. I am trying to simply fill a table with specific values by using the following:

SELECT * FROM tbl_Example
INSERT INTO tbl_Example ([Name])
VALUES ('Example1'),
('Example2'),
('Example3'), 
('Example4')

I am using the exact same code/format to fill 3 other tables in the database and do not receive an error for any of them besides this one. Cannot figure it out.

Edit: DBMS is SQL Server

Answer

The problem is that columns not included in the INSERT are set to their default values. The default “default” is NULL, which is why you are getting your error.

Check your definition of Example. Normally, a column called ExampleId would be an identity column. So, it should look like:

CREATE TABLE tbl_Example (
    ExampleId INT IDENTITY(1, 1) PRIMARY KEY,
    Name VARCHAR(?)
);

The IDENTITY() serves as a default value. It is a generally increasing sequence of values, based on insertion order.

With this definition, your code will work:

INSERT INTO tbl_Example ([Name])
VALUES ('Example1'),
       ('Example2'),
       ('Example3'), 
       ('Example4');

I would not recommend explicitly inserting the values of a primary key. There are some situations where you want to do that, but as a general rule, automatically generating keys is preferable (if you want to avoid errors on inserts).