Cannot add primary key

Question

I imported an excel file with the data I need into Sql Server. Now I want to add a primary key using this statement:

alter table Tickets add constraint idTicket primary key (TOC);;

But I get this error:

Msg 8111, Level 16, State 1, Line 1 Cannot define PRIMARY KEY constraint on nullable column in table 'Tickets'. Msg 1750, Level 16, State 0, Line 1 Could not create constraint or index. See previous errors.

I looked but couldn't find a solution here. How can I fix this?

Per the message, a primary key must be non-`NULL` and the column must therefore also be defined as such. `TOC` will need to be altered to be non-`NULL` (the statement for this depends on the type of `TOC`). — Jeroen Mostert, Jul 24 '19 at 14:19
Just usually means one of your columns (idTicket) allows nulls which cannot be for a primary key, just go to the table design and uncheck the allow nulls box on the column you wish to make the primary key. — K.Madden, Jul 24 '19 at 14:20

score 1 · Accepted Answer · answered Jul 24 '19 at 14:24

1

ALTER TABLE Tickets
ALTER TOC INT NOT NULL
GO

Then do your query to add the primary key

answered Jul 24 '19 at 14:24

K.Madden

353
1
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would you know how to delete duplicate values in my table cause i need to delete those rows and keep my table only with unique values – RagingDeathWish Jul 24 '19 at 14:43
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@RagingDeathWish: That's [another question altogether](https://stackoverflow.com/q/18932/4137916). – Jeroen Mostert Jul 24 '19 at 14:49
[everybody, in chorus] "That's another question." – Brian Jul 24 '19 at 15:31
1

\*/me slaps @Brian with a large trout\* – Jeroen Mostert Jul 24 '19 at 15:36

Cannot add primary key

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