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Sometimes, a particular field in a database row has a value that is either unknown or undefined. An example might be the termination date of an employee who is still employed by the company. A date field would not accept any value that was not a valid date but no date has been determined for the field as yet. A null would indicate that.
Wiki User
∙ 7y ago
Wiki User
∙ 12y agoits is just a blank value that is represented by the null word...
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Enter on the database or in the database?
We would use in rather than on. Data is stored in a database, not on a database. Data is entered into a database not onto a database.
What is active database and cloud database?
The database we use in our daily life is called as active database . The data that is stored in the database which is further stored on the cloud is called cloud database.
What are field can be used as primary key?
A field or set a of fields Êin a database tableÊwith unique values Êcan be used as a primary key.ÊPrimary key field cannot have a null value.
What is difference between null value and not null value?
Putting it very simply a null value is empty and a not null value contains something.
Data conversion and loading in database?
By data conversion we mean the data is first processed. The data after processing is ready to store in database. And from the database we can retrieve it for our use.
What are the three interpretations for null values?
In a database it can be 'not known' or 'not applicable'.
What is the use of nulls in a database?
Usually there is no use of nulls but in some case there might be some use. Like consider a case a persons address has been changed but the new address is not known. In this case it is prefer to left the field null instead of wrong address.
Why null values in database?
The 'null'-content of any given field is just that. It's a 'nothing'. Example, if you create a database to hold chemical values for instance. If the values are, for example, real nubers. That would imply that any value that has 0 in it, is just that; zero. It was beeing measured, and found to contain zero. On the other hand if a value was not tested, the value of that compound should be set to 'null'. If a 'null' value isn't supported by the database a workaround is to set 'null' values to -1 (as per the example above). --
Can you insert primary key only to one field in the database?
Yes. Primary key can be inserted to one field in the database. The field should be unique and not null.
What is meant by a mandatory field?
a mandatory field in a database is one created in a table as "Not null". This means, there is a "rule" on the field that when data is inserted into the table, this field cannot be empty. If it is, then the insert errors. Here's part of a table definition in my database. These field are are required to be populated when inserting into this table. ATTR_DESC_01 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_02 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_03 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_04 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_05 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_06 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_07 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_08 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_09 CHAR(2) DEFAULT SYSTEM NOT NULL, ATTR_DESC_10 CHAR(2) DEFAULT SYSTEM NOT NULL, PARTITION_NBR SMALLINT NO DEFAULT NOT NULL)
On gaia how do you get the null crystal on zen gardens in zOMG?
You could get any null in any place by going to that particular place and 'attune' the null/use it to go to null chamber. When you use the null to zen gardens, it will lead you there.
What group function can be used to perform a count that includes NULL values?
You can not group a NULL value natively. You can however transform the NULL into so other unique value; dynamically, without writing this value to the database; and group by this. You would accomplish this by implementing a coalesce T-SQL expression For example lets say the MiddleName field is NULL in many cases and you want to to group by these.. You might want to turn this NULL into say an * for purposes of giving a value that you can group by. Now you can group by all MiddleName entries and also use a where clause to excluded those values <> * giving you a sub grouping of those records ONLY having null. The SQL command would look something like this: SELECT coalesce(MiddleName, '*') FROM YourTableNameHere WHERE MiddleName LIKE '*' GROUP BY MiddleName The coalesce returns the first NON NULL value in the chain(you can have more than two values). In the above example you will get the MiddleName if there is one and an * if the database value is NULL. This is a SELECT so there is NO update to the database.
Can You insert a row containing a null attribute value using SQL?
Yes, you can insert a row with a null attribute value using SQL by simply not specifying a value for that attribute in the INSERT statement or explicitly using the keyword NULL. For example, if you have a column called "email" and want to insert a row without specifying an email value, you can do so by executing: INSERT INTO table_name (email) VALUES (NULL);
What are the advantages of performing a database normalization?
There are many advantages of performing a database normalization. Some of the advantages include faster index searching, data commands are faster with less indexes and a more compact database with less null data.
What is null on FarmVille?
its just an programming error in farmville .it would soon be alright null definition in Programming : A special value used in several languages to represent the thing referred to by an uninitialised pointer/database
What is the null in Farmville?
its just an programming error in farmville .it would soon be alright null definition in Programming : A special value used in several languages to represent the thing referred to by an uninitialised pointer/database
What is null in Farmville?
its just an programming error in farmville .it would soon be alright null definition in Programming : A special value used in several languages to represent the thing referred to by an uninitialised pointer/database
