InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
What Is A Null? |
|
Answer» A null is the absence of a value in a column of a ROW. Nulls indicate MISSING, unknown, or INAPPLICABLE data. A null should not be used to imply any other value, such as zero. A column allows nulls unless a NOT NULL or PRIMARY KEY INTEGRITY constraint has been DEFINED for the column, in which case no row can be inserted without a value for that column. A null is the absence of a value in a column of a row. Nulls indicate missing, unknown, or inapplicable data. A null should not be used to imply any other value, such as zero. A column allows nulls unless a NOT NULL or PRIMARY KEY integrity constraint has been defined for the column, in which case no row can be inserted without a value for that column. |
|