I have a sql server nvarchar field with a "Default Value or Binding" of empty string. It also happens to be a not null field.
Does this mean that there is no default or that it is a default of a string with no characters in it.
If I don't insert a value, will it insert with an empty string or fail with a "not null" error?
The default is a blank (empty) string.
If you don't provide a value, the insert will be successful and the value will be blank, not null.
Its the same as (assuming data is the col in question):
create table #t (id int, data varchar(100) not null default(''))
So:
insert into #t (id) values (1)
insert into #t (id,data) values (2,default)
insert into #t (id,data) values (3, 'allowed')
select * from #t
will return
1
2
3 allowed
and ..
insert into #t (id,data) values (1, null)
-- will error
If you have a true empty string as a default, then it will autopopulate with a 0 length string.
You should be careful to ensure it is a 0 length string and not nothing though. If for instance you are looking in the table builder gui for SSMS and it shows a blank for "Default Value or Binding", that means that there is no default value and an insert will fail if it is not populated. If you want it to have a 0 length string, populate it with '' (two single-quotes together with nothing in between.)
Default value for a column is just that - sql server will put that value when you dont supply one for the column. The value in the column will be an empty string. Not null error will not happen
Related
This seems like a trivial question. And it is. But I have googled for over a day now, and still no answer:
I wish to do a bulk insert where for a column whose datatype is varchar(100), I wish to insert an empty string. Not Null but empty. For example for the table:
create table temp(columnName varchar(100))
I wish to insert an empty string as the value:
BULK INSERT sandbox..temp FROM
'file.txt' WITH ( FIELDTERMINATOR = '|#', ROWTERMINATOR = '|:' );
And the file contents would be row1|:row2|:|:|:. So it contains 4 rows where last two rows are intended to be empty string. But they get inserted as NULL.
This question is not the same as the duplicate marked question: In a column, I wish to have the capacity to insert both: NULL and also empty-string. The answer's provided does only one of them but not both.
Well instead of inserting empty string explicitly like this why not let your table column have a default value of empty string and in your bulk insert don't pass any values for those columns. Something like
create table temp(columnName varchar(100) default '')
I am pretty new in Microsoft SQL Server and I am not so into DB in general.
I have the following doubt about an insert query that begin in this way:
insert into MyTable DEFAULT VALUES
What exactly mean the DEFAULT VALUES specification?
Tnx
Andrea
Reading the fine manual yields:
DEFAULT VALUES
Forces the new row to contain the default values defined for each column.
Well it uses the default values specified in your table.
So for example if you have a column CreationDate datetime default(getdate()) it will use it.
If each of the required columns in MyTable has specified DEFAULT VALUE then this statement insert such a row.
For example you could have column Date with default 01/01/2014 and position with DEFAULT 'Developer' and this statement would insert such a record.
You can read more here: http://msdn.microsoft.com/en-us/library/aa933206%28SQL.80%29.aspx
You can watch default specifications in work by checking that code:
DECLARE #tmp as table
(
id int null,
num int null default(777),
txt varchar(10) null default('abc'),
date datetime null
)
insert into #tmp DEFAULT VALUES
select * from #tmp
Output is
id num txt date
NULL 777 abc NULL
How do I create a table in SQL server with the default DateTime as empty, not 1900-01-01 00:00:00.000 that I get?
I mean, if there is no value inserted, the default value should be null, empty, etc.
if there is no value inserted, the default value should be null,empty
In the table definition, make this datetime column allows null, be not defining NOT NULL:
...
DateTimeColumn DateTime,
...
I HAVE ALLOWED NULL VARIABLES THOUGH.
Then , just insert NULL in this column:
INSERT INTO Table(name, datetimeColumn, ...)
VALUES('foo bar', NULL, ..);
Or, you can make use of the DEFAULT constaints:
...
DateTimeColumn DateTime DEFAULT NULL,
...
Then you can ignore it completely in the INSERT statement and it will be inserted withe the NULL value:
INSERT INTO Table(name, ...)
VALUES('foo bar', ..);
Even if your column is nullable, inserting an empty string will set the value to 1900-01-01 00:00:00.000. Make you insert real nulls not strings, then the db will store a null.
define it like your_field DATETIME NULL DEFAULT NULL
dont insert a blank string, insert a NULL INSERT INTO x(your_field)VALUES(NULL)
Ozi, when you create a new datetime object as in
datetime foo = new datetime();
foo is constructed with the time datetime.minvalue()
in building a parameterized query, you could check to see if the values entered are equal to datetime.minvalue()
-Just a side thought. seems you have things working.
I was having the same issue this morning. It appears that for a DATE or DATETIME field, an empty value cannot be inserted. I got around this by first checking for an empty value (mydate = "") and if it was empty setting mydate = "NULL" before insert.
The DATE and DATETIME fields don't behave in the same way as VARCHAR fields.
you can use like this:
string Log_In_Val = (Convert.ToString(attenObj.Log_In) == "" ? "Null" + "," : "'" + Convert.ToString(attenObj.Log_In) + "',");
A SAMPLE table has only one column ID of type int, default null.
In Oracle when I do:
insert into SAMPLE (ID) values ('');
the new record is added with blank value. But in SQL Server 2008, when I run the same insert statement, the new record has the value of 0.
Is there a way to force SQL Server 2008 to default blank string to NULL instead of 0 (for numerical type of columns)?
Assuming that your INSERT statement is part of a stored procedure re-used in many places of your application (or, perhaps, is a batch always constructed by the same part of the client code) and that the inserted value is a number passed as a string argument, you could modify the INSERT like this:
INSERT INTO SAMPLE (ID) VALUES (NULLIF(#argument, ''));
Use NULL instead.
insert into SAMPLE (ID) values (NULL);
How about another idea - define an INSTEAD OF INSERT Trigger.
Despite the fact that you're trying to insert a string, with this the operation is "intercepted", empty string is replaced by NULL, and the insert succeeds.
If you define this trigger on your table, then you can continue to insert empty string as before, with no other changes.
Edit: As Martin Smith points out, this effectively is a comparison to 0 (the equivalent of empty string as an int) meaning you won't be able to store 0 in this table. I leave this answer here in case that's acceptable to your situation - either that or re-do all your queries!
CREATE TRIGGER EmptyStringTrigger
ON [SAMPLE]
INSTEAD OF INSERT
AS
BEGIN
INSERT INTO [SAMPLE](ID)
SELECT CASE
WHEN ID = '' THEN NULL
ELSE ID
END
FROM inserted
END
SQL Fiddle example
You can't insert a 'string' into a int column. Oracle must be just handling that for you.
Just try inserting NULL if that's what you need.
insert into SAMPLE (ID) values (NULL);
One more option
insert into SAMPLE (ID) values (DEFAULT)
I have a requirement to insert the literal value 'NULL' into a nvarchar column as a default value. But when I insert records the default is going as db NULL instead of the literal 'NULL'. Can someone tell me where I am going wrong?
So you want the actual string of "NULL" to be inserted? Try something like this:
create table NullTable
(
nvarchar(100) not null default 'NULL',
.... -- your other fields
)
EDIT: Here is a full solution
create table InsertNull
(
Nullfield nvarchar(100) not null default 'NULL',
someint int not null
)
go
insert into insertnull(someint)
select 20
select *
from InsertNull
Note the quotes:
INSERT INTO yourtable (varcharfield) VALUES ('NULL'); // string null
INSERT INTO yourtable (varcharfield) VALUES (NULL); // actual null
If set the default in code instead of the designer is should work.
ALTER TABLE [myTable] ADD DEFAULT ('NULL') FOR [TextColumn]