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'ANSI null default' help

Posted on 2006-06-12
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Last Modified: 2012-08-13
Hi,

I am after some help. Can anybody tells me what happens when I use this code:

EXEC sp_dboption 'pubs','ANSI null default','false'
GO
CREATE TABLE t1 (a tinyint)
GO
INSERT INTO t1 (a) VALUES (null)
GO
SET ANSI_NUL_DFLT_ON ON
GO
CREATE TABLE t2 (a tinyint)
Go
INSERT INTO t2 (a) VALUES (null)
GO
SET ANSI_NULL_DFLT_ON OFF
GO
CREATE TABLE t3 (a tinyint)
GO
INSERT INTO t3 (a) VALUES (null)
GO
EXEC sp_dboption 'pubs','ANSI null default','true'
GO
CREATE TABLE t4 (a tinyint)
GO
INSERT INTO t4 (a) VALUES (null)
GO
SET ANSI_NUL_DFLT_ON ON
GO
CREATE TABLE t5 (a tinyint)
GO
INSERT INTO t5 (a) VALUES (null)
Go
SET ANSI_NUL_DFLT_ON OFF
GO
CREATE TABLE t6 (a tinyint)
GO
INSERT INTO t6 (a) VALUES (null)
Go
EXEC sp_dboption 'pubs','ANSI null default','false'
GO
0
Comment
Question by:alcojoe
2 Comments
 
LVL 4

Accepted Solution

by:
indu_mk earned 500 total points
ID: 16883899
This is the output
==================================================================
Server: Msg 515, Level 16, State 2, Line 1
Cannot insert the value NULL into column 'a', table 'pubs.dbo.t1'; column does not allow nulls. INSERT fails.
The statement has been terminated.

(1 row(s) affected)

Server: Msg 515, Level 16, State 2, Line 1
Cannot insert the value NULL into column 'a', table 'pubs.dbo.t3'; column does not allow nulls. INSERT fails.
The statement has been terminated.

(1 row(s) affected)


(1 row(s) affected)


(1 row(s) affected)
===================================================================

SET ANSI_NULL_DFLT_ON has an effect when the 'ANSI null default' for the database is false.
SET ANSI_NULL_DFLT_ON has no effect when the 'ANSI null default' for the database is true


EXEC sp_dboption 'pubs','ANSI null default','false'
---------- new column value will be NOT NULL by default

CREATE TABLE t1 (a tinyint)
---------- a will be a NOT NULL column

INSERT INTO t1 (a) VALUES (null)
---------- as a is a NOT NULL column, this insert stmt raises an error

SET ANSI_NULl_DFLT_ON ON
---------- for this session deafult null for new columns in enabled (ON)

CREATE TABLE t2 (a tinyint)
---------- a will be a NULLABLE column

INSERT INTO t2 (a) VALUES (null)
----------  1 row inserted

SET ANSI_NULL_DFLT_ON OFF
---------- for this session deafult null for new columns in disabled (OFF)

CREATE TABLE t3 (a tinyint)
---------- a will be a NOT NULL column

INSERT INTO t3 (a) VALUES (null)
---------- as a is a NOT NULL column, this insert stmt raises an error

EXEC sp_dboption 'pubs','ANSI null default','true'
---------- new column value will be NULL by default

CREATE TABLE t4 (a tinyint)
---------- a will be a NULLABLE column

INSERT INTO t4 (a) VALUES (null)
----------  1 row inserted

SET ANSI_NULl_DFLT_ON ON
---------- for this session deafult null for new columns in enabled (ON)

CREATE TABLE t5 (a tinyint)
---------- a will be a NULLABLE column

INSERT INTO t5 (a) VALUES (null)
----------  1 row inserted

SET ANSI_NULl_DFLT_ON OFF
---------- for this session deafult null for new columns in disabled (OFF)

CREATE TABLE t6 (a tinyint)
---------- a will be a NULLABLE column

INSERT INTO t6 (a) VALUES (null)
----------  1 row inserted

EXEC sp_dboption 'pubs','ANSI null default','false'
---------- new column value will be NOT NULL by default

0
 
LVL 28

Expert Comment

by:imran_fast
ID: 16885313
from books online
==============
Allows the user to control the database default nullability. When NULL or NOT NULL is not specified explicitly, a user-defined data type or a column definition uses the default setting for nullability. Nullability is determined by session and database settings. Microsoft SQL Server™2000 defaults to NOT NULL. For ANSI compatibility, setting the database option ANSI_NULL_DEFAULT to ON changes the database default to NULL.

When this option is set to ON, all user-defined data types or columns that are not explicitly defined as NOT NULL during a CREATE TABLE or ALTER TABLE statement default to allowing null values. Columns that are defined with constraints follow constraint rules regardless of this setting.
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