DATABASE FUNDAMENTALS
DATA WAREHOUSING AND DATA MINING
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A numeric value with value 0
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The absence of a value
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A very small value
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An erroneous value
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Detailed explanation-1: -A null value is a special indicator that represents the absence of a value. The value can be absent because it is unknown, not yet supplied, or nonexistent. The DBMS treats the null value as an actual value, not as a zero value, a blank, or an empty string.
Detailed explanation-2: -A null value in a relational database is used when the value in a column is unknown or missing. A null is neither an empty string (for character or datetime data types) nor a zero value (for numeric data types).
Detailed explanation-3: -Explanation: Null is used to represent the absence of a value.
Detailed explanation-4: -A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field. Then, the field will be saved with a NULL value.
Detailed explanation-5: -A null database field means that there is no value for a given record. It indicates the absence of a value. A blank database field means that there is a value for a given record, and this value is empty (for a string value) or 0 (for a numeric value).