Primary key unique key candidate key

Answer 1

what's the question, please?

Answer 2

As far as I know, a (unique) key for a table is a column (or set of columns) such that there are no two records with the same value for that key. There can be several keys for a table. Once you choose a key to be *the* primary key for a table, the rest of keys become candidate keys.

Answer 3

what is definitioñof this keys

Answer 4

Your primary key is the column name which has to have a unique value for every entry in the table. It is a unique identifier in the case that you need to join more than one table together that have the same column name. For example if you had a primary key named accountnum in table A and then a column named the same thing in table B you could join the tables. The accountnum in table A will be the primary key, and the accountnum in table B will be the foreign key.

Answer 5

PIN kódem