how can I create a Column with the default value being an empty string?
thanks guys!
You can read up on the subject here
CREATE TABLE dbo.Test (ID INTEGER, EmptyString VARCHAR(32) DEFAULT '')
INSERT INTO dbo.Test (ID) VALUES (1)
INSERT INTO dbo.Test (ID) VALUES (2)
SELECT * FROM dbo.Test
DROP TABLE dbo.Test
Something like:
CREATE TABLE foobar (string_column VARCHAR(100) NOT NULL DEFAULT '')
In SQL server you can set "Column properties > Default value or binding" section to (''). NOTE: It includes single quotation and parenthesis
Related
I am trying to generate a sequence varchar text type, but I do not want to have to create another column to get the id to format it and insert it I want to generate it in the same column, help
create table tbl (
Id int identity not null,
CusId as 'CUS' + format(Id, '00000'),
-- ...
)
You can use sequence object that appeared in SQL Server 2012 + default value like this:
create sequence dbo.ids as int
minvalue 1;
create table dbo.tbl (
CusId varchar(100) default 'CUS' + format(NEXT VALUE FOR dbo.ids, '00000'));
insert into dbo.tbl (CusId) default values;
insert into dbo.tbl (CusId) default values;
insert into dbo.tbl (CusId) default values;
select *
from dbo.tbl;
-----
--CusId
--CUS00001
--CUS00002
--CUS00003
Believe the only viable solution is using 2 columns as you mentioned, and discussed here:
Autoincrement of primary key column with varchar datatype in it
Have not seen it achieved in a single column on its own.
These is my example table definition:
CREATE TABLE [MyTable]
(
[ColumnName] [bit] NOT NULL
)
ALTER TABLE [MyTable] ADD DEFAULT ((0)) FOR [ColumnName]
I want to be able to pass a Null value to my stored procedure's #ColumnValue, something like:
#ColumnValue = null;
INSERT INTO [MyTable] ([ColumnName])
VALUES (#ColumnValue)
But I'm getting this error:
"Cannot insert the value NULL into column... INSERT fails with"
Why the DEFAULT constraints not working?
Solved:
as #J.D. Pace said: The default value will be inserted only if the value is not specified on the Insert statement.
so as #dotNET suggested, i have specified the default value in the INSERT query statement using the ISNULL:
ISNULL - The SQL Server ISNULL() function lets you return an alternative value when an expression is NULL:
#ColumnValue = null;
INSERT INTO [MyTable] (
[ColumnName]
)
VALUES (
ISNULL(#ColumnValue, 0)
)
A table with only one column of bit type with a default value seems to be a bad design. This stuff can almost certainly be stored in a different and better way. On the other hand, if there are other columns in the table that you didn't include in the post, just skip this particular column in your INSERT query and it will work fine. Lastly, you can specify the default value in your INSERT query too.
i'm trying to have a table with a column that has a default value.
right now i can only get this by having a trigger change the value to the default, is it possible to have it declared on the table right from the start?
Would it be possible to have something like the Identity, where i don't have to pass the value into the insert?
egx: insert into Direct values(2)
and the table would become
id | item
1 | 2
the id = 1, would be the deafult value
thanks in advance!
you can create constraints at time of table creation or later.
create table
#test
(
id int identity(1,2),
name char(255) default newid(),
code int default 2
)
---if a table contains all default values,you can insert like below
insert into #test
default values
updated as per comments:
create table
#test1
(
id int identity(1,2),
name char(255) default newid(),
code int default 2,
notdf int
)
---if a table contains one default value and rest all are default
insert into #test1(notdf)
select 2
Further if you want to add a default value after table creation you can do it like below
create table
tt1
(
valuue int,
address char(2) not null
)
insert into tt1
select 1,'a'
ALTER TABLE tt1 ADD CONSTRAINT test1 DEFAULT null FOR address;
Use default. You can change an existing column by doing:
ALTER TABLE t ADD CONSTRAINT df_t_column DEFAULT 1 for id;
An identity is trickier. I would suggest copying the data over to a temporary table, dropping the table, creating it with an identity column and reloading the data.
How to add a column to a SQL Server table with a default value that is equal to value of an existing column?
I tried this T-SQL statement:
ALTER TABLE tablename
ADD newcolumn type NOT NULL DEFAULT (oldcolumn)
but it's giving an error:
The name "oldcolumn" is not permitted in this context. Valid
expressions are constants, constant expressions, and (in some
contexts) variables. Column names are not permitted.
Try this:
ALTER TABLE tablename ADD newcolumn type NOT NULL DEFAULT (0)
Go
Update tablename SET newcolumn = oldcolumn Where newcolumn = 0
Go
The AFTER INSERT trigger approach involves overhead due to the extra UPDATE statement. I suggest using an INSTEAD OF INSERT trigger, as follows:
CREATE TRIGGER tablename_on_insert ON tablename
INSTEAD OF INSERT
AS
INSERT INTO tablename (oldcolumn, newcolumn)
SELECT oldcolumn, ISNULL(newcolumn, oldcolumn)
FROM inserted
This does not work though if the oldcolumn is an auto-identity column.
I don't like them very much but here is how you could do this with an AFTER INSERT trigger:
CREATE TRIGGER TableX_AfterInsert_TRG
ON TableX
AFTER INSERT
AS
UPDATE TableX AS t
SET t.newcolumn = t.oldcolumn
FROM Inserted AS i
WHERE t.PK = i.PK ; -- where PK is the PRIMARY KEY of the table
You can use computed column to insert new column in a table based on an existing column value
ALTER TABLE dbo.TableName ADD NewColumn AS (OldColumn) PERSISTED;
OR, if you want to make some changes to the value based on existing column value, use
ALTER TABLE dbo.TableName ADD NewColumn AS (OldColumn * 1.5) PERSISTED;
To extend Kapil's answer, and avoid the unwanted default constraint, try this:
ALTER TABLE tablename ADD newcolumn type NOT NULL CONSTRAINT DF_TMP_TABLENAME_NEWCOLUMN DEFAULT -9999
Go
Update tablename SET newcolumn = oldcolumn
Go
ALTER TABLE tablename DROP CONSTRAINT DF_TMP_TABLENAME_NEWCOLUMN
Go
Replace -9999 by 'noData' if your type is varchar, nvarchar, datetime,... or by any compatible data for other types: specific value doesn't matter, it will be wiped by the 2nd instruction.
For my case, I want to add a new not null unique column named CODE but I don't know about the value at the creation time. I set the default value for it by get a default value from NewID() then update later.
ALTER TABLE [WIDGET] ADD [CODE] CHAR(5) NOT NULL DEFAULT(SUBSTRING(CONVERT(CHAR(36), NEWID()), 1, 5))
ALTER TABLE [dbo].[WIDGET] WITH CHECK ADD CONSTRAINT [UQ_WIDGET_CODE] UNIQUE ([CODE])
Use a computed column, which will even work with IDENTITY column values:
CREATE TABLE #This
( Id INT IDENTITY(1,1)
,MyName VARCHAR(10)
,FullName AS (Myname + CONVERT(VARCHAR(10),Id)) PERSISTED);
INSERT #This VALUES ('Item'),('Item');
SELECT * FROM #This;
DROP TABLE #This;
yields the following:
I think it will work if you use Set Identity_Insert <TableName> OFF and after the insert Statement that you wrote just use Set Identity_Insert <TableName> ON.
can anyone please tell me the right way to insert values in the rowguid column of the table? I m using sql server management studio
use the NEWID() function to generate one:
CREATE TABLE myTable(GuidCol uniqueidentifier
,NumCol int)
INSERT INTO myTable Values(NEWID(), 4)
SELECT * FROM myTable
or you can set it as a default value:
CREATE TABLE myTable(GuidCol uniqueidentifier DEFAULT NEWSEQUENTIALID()
,NumCol int)
INSERT INTO myTable (NumCol) Values(4)
SELECT * FROM myTable
You can Set NEWSEQUENTIALID() as Default in table
CREATE TABLE GuidTable
(
ID UNIQUEIDENTIFIER DEFAULT NEWSEQUENTIALID() PRIMARY KEY,
TEST INT
)
Read more about it here
http://msdn.microsoft.com/en-us/library/ms189786.aspx
It's a uniqueidentifier column
You can send a value like "6F9619FF-8B86-D011-B42D-00C04FC964FF", or use NEWID/NEWSEQUENTIALID functions to generate one
I was able to insert by using the following:
Insert Into Table FOO(Col1, Col2, RowGuidCol)
Values (5,'Hello,'1A49243F-1B57-5848-AA62-E4704544BB34')
It is very important to follow to place the dashes in the correct place. You do not need to have the 0x in the beginning of the string. FYI-Updates are not allow on columns whith the rowguid col property set. I hope this helps.
Assuming that you have a uniqueidentifier column rg in your table t which is set to be the rowguid:
INSERT INTO TABLE t (rg) VALUES (NEWID())
or
INSERT INTO TABLE t (rg) VALUES (NEWSEQUENTIALID())