How to pass data type NULL?

Question

What is the data type for NULLwhen passing this value without any data to the database?

Answer 1

There is type NO data NULL. NULL itself means NO data. When there is no data, how can it have a type?

Answer 2

Null does not have a specific data type in SQL. Any null column or variable can contain zero. Zero is never equal or unequal to anything. You can apply a variable holding null to another variable and get zero, for example:

declare @a integer
set @a = null
select convert (float, @a)

----------------------
NULL

(1 row(s) affected)

Answer 3

NULL 0: INTEGER, FLOAT VARCHAR. .

NULL , .

RDBMS.

SQLite, , , , NULL - .

Oracle . , :

SELECT  COALESCE(dt, i)
FROM    (
        SELECT  CAST(NULL AS DATE) AS dt, CAST(NULL AS DATE) i
        FROM    dual
        ) q

:

SELECT  COALESCE(dt, i)
FROM    (
        SELECT  CAST(NULL AS DATE) AS dt, CAST(NULL AS NUMBER) i
        FROM    dual
        ) q

, NULL, COALESCE , .

, NULL NULL .

, a VARCHAR INTEGER, 0, , 'some_string'.

NULL, , .

Answer 4

NULL - 'undefined'. , "undefined", : "undefined", "NULL", , . .

Answer 5

, DBNULL NULL - .

Answer 6

NULL - 1 "INTEGER", NULL - "NULL"

Answer 7

http://en.wikipedia.org/wiki/Null_(SQL)

Answer 8

, . NULL , . , , ?

NULL==NULL

.

Answer 9

, PowerShell $null -eq $null False. , -Not $null True, , False. , PowerShell , :)

Answer 10

SQL NULL "" ( , ), SQL. .

Answer 11

SQL NULL . . postgresql derby (javadb) , null . , . , , NULL IS NULL, . NULL - , NULL. , , .

. CAST: - NULL

. fail setObject ( arg, null)

, , .

Answer 12

Prabhahar, NULL. API- .

, Java Derby, Java, null, Ian Bjorhovde "Derby Handling of NULL Values" :

insert into T_AUTHOR (
  ID, FIRST_NAME, LAST_NAME, 
  DATE_OF_BIRTH, YEAR_OF_BIRTH, ADDRESS) 
VALUES ( 
  1000, 'Lukas', 'Eder', 
  '1981-07-10', null, null 
);

NULL JDBC: null Integer:

pst.setNull(4, java.sql.Types.INTEGER);

Answer 13

NULL () , NULL FALSE.