July 30, 2014 at 8:47 am
Hello,
During the installation of SQL Server or even after installed, it is possible to define some types of fields with value?
Is required to set the null value after the field type?
What can happen if null is not defined?
example:
create table Table1(
...
ExpirationDate datetime null,
ExpirationDate datetime, -- always have a value ?
...);
Thank you very much!
JoseAcJR
July 30, 2014 at 8:50 am
Is required to set the null value after the field type?
It is not required.
What can happen if null is not defined?
If you don't set the NULL option then it will be nullable.
create table Test1 (
ExpirationDate datetime);
go
July 30, 2014 at 8:56 am
Ok, but let me explain better:
During the installation of SQL Server or even once installed, can we define default value for some types (eg DateTime) for all tables that pass to be created?
Thanks
July 30, 2014 at 9:05 am
You can create User Defined Data Types that had the necessary Null values you want defaulted for that data type, but you would have to use that data type when creating tables. I don't believe that you can alter the existing data types.
July 30, 2014 at 9:29 am
JoseACJr (7/30/2014)
Ok, but let me explain better:During the installation of SQL Server or even once installed, can we define default value for some types (eg DateTime) for all tables that pass to be created?
Thanks
NO. As Keith said you would have to use a user defined datatype.
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July 30, 2014 at 9:44 am
Keith Tate (7/30/2014)
What can happen if null is not defined?
If you don't set the NULL option then it will be nullable.
create table Test1 (ExpirationDate datetime);
go
That's not true. The default could be NULL or NOT NULL, and which one can be influenced by both database and/or session settings. Therefore, you should always explicitly specify "NULL" or "NOT NULL" on every column, since you won't know the database and/or session settings if/when the code is run again if the future.
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.
July 30, 2014 at 10:03 am
ScottPletcher (7/30/2014)
Keith Tate (7/30/2014)
What can happen if null is not defined?
If you don't set the NULL option then it will be nullable.
create table Test1 (ExpirationDate datetime);
go
That's not true. The default could be NULL or NOT NULL, and which one can be influenced by both database and/or session settings. Therefore, you should always explicitly specify "NULL" or "NOT NULL" on every column, since you won't know the database and/or session settings if/when the code is run again if the future.
I agree we should always define NULL or NOT NULL. What settings can change or influence this? I am not familiar with that.
_______________________________________________________________
Need help? Help us help you.
Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.
Need to split a string? Try Jeff Modens splitter http://www.sqlservercentral.com/articles/Tally+Table/72993/.
Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/
July 30, 2014 at 10:08 am
Sean Lange (7/30/2014)
ScottPletcher (7/30/2014)
Keith Tate (7/30/2014)
What can happen if null is not defined?
If you don't set the NULL option then it will be nullable.
create table Test1 (ExpirationDate datetime);
go
That's not true. The default could be NULL or NOT NULL, and which one can be influenced by both database and/or session settings. Therefore, you should always explicitly specify "NULL" or "NOT NULL" on every column, since you won't know the database and/or session settings if/when the code is run again if the future.
I agree we should always define NULL or NOT NULL. What settings can change or influence this? I am not familiar with that.
From Books Online.
"
If the system-supplied data type has only one option, it takes precedence. timestamp data types must be NOT NULL.
When any session settings are set ON by using SET:
ANSI_NULL_DFLT_ON = ON, NULL is assigned.
ANSI_NULL_DFLT_OFF = ON, NOT NULL is assigned.
When any database settings are configured by using ALTER DATABASE:
ANSI_NULL_DEFAULT_ON = ON, NULL is assigned.
ANSI_NULL_DEFAULT_OFF = ON, NOT NULL is assigned.
When neither of the ANSI_NULL_DFLT options is set for the session and the database is set to the default (ANSI_NULL_DEFAULTis OFF), the default of NOT NULL is assigned.
"
Hmm, yeah, I'm not gonna try to guess the current state of all that, I'm just gonna code "NULL" or "NOT NULL" and be done with it :-D.
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.
July 30, 2014 at 10:17 am
ScottPletcher (7/30/2014)
Sean Lange (7/30/2014)
ScottPletcher (7/30/2014)
Keith Tate (7/30/2014)
What can happen if null is not defined?
If you don't set the NULL option then it will be nullable.
create table Test1 (ExpirationDate datetime);
go
That's not true. The default could be NULL or NOT NULL, and which one can be influenced by both database and/or session settings. Therefore, you should always explicitly specify "NULL" or "NOT NULL" on every column, since you won't know the database and/or session settings if/when the code is run again if the future.
I agree we should always define NULL or NOT NULL. What settings can change or influence this? I am not familiar with that.
From Books Online.
"
If the system-supplied data type has only one option, it takes precedence. timestamp data types must be NOT NULL.
When any session settings are set ON by using SET:
ANSI_NULL_DFLT_ON = ON, NULL is assigned.
ANSI_NULL_DFLT_OFF = ON, NOT NULL is assigned.
When any database settings are configured by using ALTER DATABASE:
ANSI_NULL_DEFAULT_ON = ON, NULL is assigned.
ANSI_NULL_DEFAULT_OFF = ON, NOT NULL is assigned.
When neither of the ANSI_NULL_DFLT options is set for the session and the database is set to the default (ANSI_NULL_DEFAULTis OFF), the default of NOT NULL is assigned.
"
Hmm, yeah, I'm not gonna try to guess the current state of all that, I'm just gonna code "NULL" or "NOT NULL" and be done with it :-D.
Agreed about not guessing. Was curious about what settings as I didn't know about them so had no idea where to start. Thanks for the info. Good to know.
_______________________________________________________________
Need help? Help us help you.
Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.
Need to split a string? Try Jeff Modens splitter http://www.sqlservercentral.com/articles/Tally+Table/72993/.
Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/
July 30, 2014 at 10:30 am
ScottPletcher (7/30/2014)
Sean Lange (7/30/2014)
ScottPletcher (7/30/2014)
Keith Tate (7/30/2014)
What can happen if null is not defined?
If you don't set the NULL option then it will be nullable.
create table Test1 (ExpirationDate datetime);
go
That's not true. The default could be NULL or NOT NULL, and which one can be influenced by both database and/or session settings. Therefore, you should always explicitly specify "NULL" or "NOT NULL" on every column, since you won't know the database and/or session settings if/when the code is run again if the future.
I agree we should always define NULL or NOT NULL. What settings can change or influence this? I am not familiar with that.
From Books Online.
"
If the system-supplied data type has only one option, it takes precedence. timestamp data types must be NOT NULL.
When any session settings are set ON by using SET:
ANSI_NULL_DFLT_ON = ON, NULL is assigned.
ANSI_NULL_DFLT_OFF = ON, NOT NULL is assigned.
When any database settings are configured by using ALTER DATABASE:
ANSI_NULL_DEFAULT_ON = ON, NULL is assigned.
ANSI_NULL_DEFAULT_OFF = ON, NOT NULL is assigned.
When neither of the ANSI_NULL_DFLT options is set for the session and the database is set to the default (ANSI_NULL_DEFAULTis OFF), the default of NOT NULL is assigned.
"
Hmm, yeah, I'm not gonna try to guess the current state of all that, I'm just gonna code "NULL" or "NOT NULL" and be done with it :-D.
Thanks for the info Scott!
July 30, 2014 at 11:10 am
Thanks everyone, it was exactly the explanation I needed to get!
😀
JoseAcJR
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