Change Varchar data type to primary key

Question

Hello i am curently trying to set up a data base in MYSQL and i want to have my Varchar element as the Primary Key but it always gives me an error like this:

Invalid use of NULL value

the command i am using is:

ALTER  TABLE temp_keys ADD PRIMARY KEY (temp_key);

and here is how the table is set up:

Intel

I hope that some one of you can help me with this.

Does this answer your question? [NULL value in multi-column primary key](https://stackoverflow.com/questions/11001333/null-value-in-multi-column-primary-key) — P.Salmon, Apr 07 '22 at 07:11
Also PRIMARY KEY A unique index where all key columns must be defined as NOT NULL - https://dev.mysql.com/doc/refman/8.0/en/create-table.html — P.Salmon, Apr 07 '22 at 07:15

score 0 · Answer 1 · answered Apr 07 '22 at 08:52

VARCHAR data type is not a problem. PRIMARY KEY columns must be defined as NOT NULL. Append CHANGE temp_key temp_key VARCHAR (50) NOT NULL in your query and change value(50) according to your need.

Just execute ALTER TABLE temp_keys CHANGE temp_key temp_key VARCHAR (50) NOT NULL, ADD PRIMARY KEY (temp_key);

Change Varchar data type to primary key

1 Answers1