In the context of a
relational database table, a
column is a set of
data values of a particular simple
type, one for each
row of the table. The columns provide the structure according to which the rows are composed. When a column allows data values of a single type, it does not essentially mean it only has simple text values. Other databases go beyond and let the data be stored as a file on Operating System whereas the column data only covers a pointer or a link to the actual file. Also, databases mostly let columns to have more complex data for example whole documents, images or even video clips.