Syntax:
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES
Example:
ALTER TABLE SomeTable
ADD SomeCol Bit NULL --Or NOT NULL.
CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.
Notes:
Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol
then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6
Optional With-Values Statement:
The WITH VALUES
is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL
, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES
or not.
How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable
and do not Specify SomeCol
's value, then it will Default to 0
.
If you insert a Record and Specify SomeCol
's value as NULL
(and your column allows nulls),
then the Default-Constraint will not be used and NULL
will be inserted as the Value.
Notes were based on everyone's great feedback below.
Special Thanks to:
@Yatrix, @WalterStabosz, @YahooSerious, and @StackMan for their Comments.
Finally I found a solution - I'm posting it here for other people who might have the same problem (all 5 of you):
- Change the product ID to *
Under product add The following:
<Property Id="PREVIOUSVERSIONSINSTALLED" Secure="yes" />
<Upgrade Id="YOUR_GUID">
<UpgradeVersion
Minimum="1.0.0.0" Maximum="99.0.0.0"
Property="PREVIOUSVERSIONSINSTALLED"
IncludeMinimum="yes" IncludeMaximum="no" />
</Upgrade>
Under InstallExecuteSequence add:
<RemoveExistingProducts Before="InstallInitialize" />
From now on whenever I install the product it removed previous installed versions.
Note: replace upgrade Id with your own GUID
Best Answer
After a day of searching, the best I have found is http://www.magsys.co.uk/delphi/.
There is a demo project which allows you to change namespaces and test various WQL and instance queries. Hope this helps someone.