what if I want to make the primary key for 2 columns together how can I name the primary key for the 2 named columns and how can we create a relation between them like (Primary key name for 2 columns) I Purchase num column I Sales column I I I I I I I I I I

Hi Peter! Thanks for reaching out. The syntax for defining a composite primary key is: PRIMARY KEY(column_1, column_2). In this case: PRIMARY KEY(Purchase_num_column, Sales_column). The names of the columns should not contain a space. Please, use an underscore for example. Hope this helps. Best, Tsvetelin