sql-server - query - sql add column with default value in select




How to set a default value for an existing column (8)

This isn't working in SQL Server 2008:

ALTER TABLE Employee ALTER COLUMN CityBorn SET DEFAULT 'SANDNES'

The error is:

Incorrect syntax near the keyword 'SET'.

What am I doing wrong?


First drop constraints

https://.com/a/49393045/2547164

DECLARE @ConstraintName nvarchar(200)
SELECT @ConstraintName = Name FROM SYS.DEFAULT_CONSTRAINTS
WHERE PARENT_OBJECT_ID = OBJECT_ID('__TableName__')
AND PARENT_COLUMN_ID = (SELECT column_id FROM sys.columns
                        WHERE NAME = N'__ColumnName__'
                        AND object_id = OBJECT_ID(N'__TableName__'))
IF @ConstraintName IS NOT NULL
EXEC('ALTER TABLE __TableName__ DROP CONSTRAINT ' + @ConstraintName)

Second create default value

ALTER TABLE [table name] ADD DEFAULT [default value] FOR [column name]

Hoodaticus's solution was perfect, thank you, but I also needed it to be re-runnable and found this way to check if it had been done...

IF EXISTS(SELECT * FROM information_schema.columns 
           WHERE table_name='myTable' AND column_name='myColumn' 
             AND Table_schema='myDBO' AND column_default IS NULL) 
BEGIN 
  ALTER TABLE [myDBO].[myTable] ADD DEFAULT 0 FOR [myColumn] --Hoodaticus
END

Like Yuck's answer with a check to allow the script to be ran more than once without error. (less code/custom strings than using information_schema.columns)

IF object_id('DF_SomeName', 'D') IS NULL BEGIN
    Print 'Creating Constraint DF_SomeName'
   ALTER TABLE Employee ADD CONSTRAINT DF_SomeName DEFAULT N'SANDNES' FOR CityBorn;
END

The correct way to do this is as follows:

  1. Run the command:

    sp_help [table name] 
    
  2. Copy the name of the CONSTRAINT.

  3. Drop the DEFAULT CONSTRAINT:

    ALTER TABLE [table name] DROP [NAME OF CONSTRAINT] 
    
  4. Run the command below:

    ALTER TABLE [table name] ADD DEFAULT [DEFAULT VALUE] FOR [NAME OF COLUMN]
    

This will work in SQL Server:

ALTER TABLE Employee ADD CONSTRAINT DF_SomeName DEFAULT N'SANDNES' FOR CityBorn;

Try following command;

ALTER TABLE Person11
ADD CONSTRAINT col_1_def
DEFAULT 'This is not NULL' FOR Address

in case a restriction already exists with its default name:

-- Drop existing default constraint on Employee.CityBorn
DECLARE @default_name varchar(256);
SELECT @default_name = [name] FROM sys.default_constraints WHERE parent_object_id=OBJECT_ID('Employee') AND COL_NAME(parent_object_id, parent_column_id)='CityBorn';
EXEC('ALTER TABLE Employee DROP CONSTRAINT ' + @default_name);

-- Add default constraint on Employee.CityBorn
ALTER TABLE Employee ADD CONSTRAINT df_employee_1 DEFAULT 'SANDNES' FOR CityBorn;

ALTER TABLE Employee ADD DEFAULT 'SANDNES' FOR CityBorn




default-value