Same elements in SQL table

Question

I try to do this in SQL:

CREATE TABLE numbers (

id INTEGER PRIMARY KEY

);

INSERT INTO numbers VALUES (1);

INSERT INTO numbers VALUES (1);

INSERT INTO numbers VALUES (2);

INSERT INTO numbers VALUES (4);

SELECT * FROM numbers;

In respons, compiler writes "UNIQUE constraint failed" and prints "1 2 4". How can I print all values without error?

Answer 1

Column "Id" is define as primary key and a PK can contain only unique values; you can not insert duplicates. You have to check if a value already exists.

Answer 2

Hi

that won't happen.

By default the PRIMARY KEY is always a UNIQUE key, so that is why you are getting the error "Unique constraint"... a row with value "1" is already existing.

And if you just insert the values 1,2,4 then the resultset is correct ;-)

And if you only execute the SELECT statement, you won't receive any error... the error comes from the insert statements.

I hope my answer is helpful to you,

Your

Bjoern Peters

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Answer 3

Hi @Большаков Георгий

As experts answered above, you cannot insert duplicate records into a column with Primary key constraint.

If you want to display 1,1,2,4 you could delete the Primary key in the code of Create table.

Best regards,

Cosmog Hong

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