There appears to be at least two ways to add a default constraint using straight T-SQL. Am I correct that the only difference between the two below is that the second method specifically creates a name for the constraint, and the first method has one generated by SQL Server?
ALTER TABLE [Common].[PropertySetting] ADD DEFAULT ((1)) FOR [Active]; ALTER TABLE [Common].[PropertySetting] ADD CONSTRAINT [DF_PropertySetting_Active) DEFAULT ((1)) FOR [Active]; Pretty much, yes for an ALTER TABLE
You can add a columnn with default in one step for CREATE or ALTER too.
ALTER TABLE dbo.TableName ADD bar varchar(100) CONSTRAINT DF_Foo_Bar DEFAULT ('bicycle'); ALTER TABLE dbo.TableName ADD bar varchar(100) DEFAULT ('bicycle'); As you noted, the system generates a name if one is not supplied. CONSTRAINT constraint_name is optional says MSDN. The same applies to any column or table CONSTRAINT
If the column was already created, and you only want to add a (named) DEFAULT constraint, then use:
ALTER TABLE dbo.TableName ADD CONSTRAINT DF_Foo_Bar DEFAULT 'bicycle' FOR FieldName; To have the system generate the DEFAULT constraint name (which will be of the form DF_{TableName}_{Column}_{8RandomChars}, e.g. DF_TableName_FieldName_12345678) then omit the CONSTRAINT <name> part, like so:
ALTER TABLE dbo.TableName ADD DEFAULT 'bicycle' FOR FieldName; 
DF_Foo_Bar, even if the column already exists?
ALTER TABLE dbo.TableName ADD DEFAULT(SYSUTCDATETIME()) FOR Created; to create a system-named constraint object. Note that the "CONSTRAINT" keyword must be omitted (which is confusing).