What is a NULL value? What are the pros and cons of using NULLS?

A NULL value takes up one byte of storage and indicates that a value is not present as opposed to a space or zero value. It's the DB2 equivalent of TBD on an organizational chart and often correctly portrays a business situation. Unfortunately, it requires extra coding for an application program to handle this situation.

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Oct 13th, 2004
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burelamanohar

Feb 6th, 2007

A NULL value indicates the absence of a column value in a row.A NULL value is not the same as ZERO or all BLANKS.

arijit.seth

Sep 29th, 2007

A NULL value is different from a blank or a zero
A NULL value can be inserted into columns of any data type
A NULL value will evaluate to NULL in any expression (e.g.NULL multiplied by 10 is NULL)
If a column has a NULL value, Oracle ignores any UNIQUE, FOREIGN KEY, CHECK constraints that may be attached to the column.