Find All NOT NULL Columns Without a Default Constraint

Rarely, I'll run into a situation where it would be useful to know which columns that are specified as NOT NULL don't have a default constraint as well. For example, I've seen a table with two dozen columns, all but a few set as NOT NULL. This in itself isn't an issue, but on this occasion, for debugging purposes, we were constantly INSERTing a test row of data into the table. Having to specify a default value for each column got to be annoying after a while.

There are, of course, other ways to skin this cat, We could have created a SSMS template and used the old "Ctrl-Shift-M" key combo to type in just the values we needed. Or we could have created a script, or even a stored procedure to handle the default values for us. For various reasons, those solutions wouldn't work in our environment, so I decided to attack the problem at its root.

The code below looks at all non-empty tables and prints out T-SQL code to add the default constraint to each column it finds. Note that I've made an attempt to select a reasonable default value for all the common data types, but (a) the list is not complete, and (b) your idea of a "reasonable" default value may be very different from mine. So don't just copy and paste the output from this script and hit F5 - take a moment to read each line and be sure it does what you want; if not, you can easily change it!

-------------------------------------------------------------------------------
-- For all tables in the current database that have rows, finds all "NOT NULL" 
-- columns that don't have a DEFAULT constraint, and emits the ALTER TABLE     
-- statements needed to add the DEFAULT constraints for them.                  
-------------------------------------------------------------------------------

SET NOCOUNT ON

DECLARE @SchemaName      sysname         SET @SchemaName     = ''
DECLARE @TableName       sysname         SET @TableName      = ''
DECLARE @ColumnName      sysname         SET @ColumnName     = ''
DECLARE @ColumnType      sysname         SET @ColumnType     = ''
DECLARE @ConstraintName  sysname         SET @ConstraintName = ''
DECLARE @Sql             NVARCHAR(MAX)   SET @Sql            = ''

DECLARE cur CURSOR FOR
    SELECT SCHEMA_NAME(t.schema_id)    AS 'Schema Name'
         , OBJECT_NAME(c.object_id)    AS 'Table Name'
         , c.name                      AS 'Column Name'
         , ty.name                     AS 'Column Type'
      FROM sys.columns   c
      JOIN sys.tables    t
        ON c.object_id = t.object_id
      JOIN sys.types     ty
        ON c.user_type_id = ty.user_type_id
     WHERE c.is_nullable                  = 0
       AND c.is_identity                  = 0
       AND c.is_computed                  = 0
       AND t.type_desc                    = 'USER_TABLE'
       AND t.is_ms_shipped                = 0
       AND ISNULL(c.default_object_id, 0) = 0
       AND 0 < (SELECT SUM(row_count)
                  FROM sys.dm_db_partition_stats
                 WHERE object_id = OBJECT_ID(t.name)   
                   AND (index_id = 0 OR index_id = 1))
  ORDER BY 'Schema Name'
         , 'Table Name'
         , 'Column Name'

OPEN cur

FETCH NEXT FROM cur
 INTO @SchemaName, @TableName, @ColumnName, @ColumnType
        
IF @@FETCH_STATUS = 0
BEGIN        
    PRINT 'USE ' + DB_NAME(0)
    PRINT ' ' 
END

WHILE @@FETCH_STATUS = 0
BEGIN
    SET @ConstraintName = QUOTENAME('DF_'+ @TableName + '_' + @ColumnName)
    
    SET @Sql = ''
             + 'PRINT ''Processing: ' + QUOTENAME(@SchemaName) + '.' + @ConstraintName + ''''
             + ' ALTER TABLE ' + QUOTENAME(@SchemaName) + '.' + QUOTENAME(@TableName) 
             + ' ADD CONSTRAINT ' + @ConstraintName 
             + ' DEFAULT ('
             +
                CASE @ColumnType
                    WHEN 'char'             THEN ''''''
                    WHEN 'nchar'            THEN ''''''
                    WHEN 'varchar'          THEN ''''''
                    WHEN 'nvarchar'         THEN ''''''
                    WHEN 'sysname'          THEN ''''''
                    WHEN 'xml'              THEN ''''''
                    WHEN 'udtUserID'        THEN ''''''
                    WHEN 'text'             THEN ''
                    WHEN 'ntext'            THEN ''

                    WHEN 'bigint'           THEN '0'
                    WHEN 'int'              THEN '0'
                    WHEN 'smallint'         THEN '0'
                    WHEN 'tinyint'          THEN '0'
                    WHEN 'bit'              THEN '0'

                    WHEN 'real'             THEN '0.0'
                    WHEN 'money'            THEN '0.0'
                    WHEN 'smallmoney'       THEN '0.0'
                    WHEN 'float'            THEN '0.0'
                    WHEN 'decimal'          THEN '0.0'
                    WHEN 'numeric'          THEN '0.0'

                    WHEN 'image'            THEN '0x0'
                    WHEN 'binary'           THEN '0x0'
                    WHEN 'varbinary'        THEN '0x0'
                    
                    WHEN 'uniqueidentifier' THEN '0x0'
                    WHEN 'sql_variant'      THEN '0'
                    WHEN 'hierarchyid'      THEN '''/'''
                    WHEN 'geometry'         THEN '0'
                    WHEN 'geography'        THEN '0'

                    WHEN 'datetime'         THEN 'GETDATE()'
                    WHEN 'date'             THEN 'GETDATE()'
                    WHEN 'time'             THEN 'GETDATE()'
                    WHEN 'datetime2'        THEN 'GETDATE()'
                    WHEN 'datetimeoffset'   THEN 'GETDATE()'
                    WHEN 'smalldatetime'    THEN 'GETDATE()'
                    WHEN 'timestamp'        THEN 'GETDATE()'
                    ELSE                         '-1'
                END
                    
             + ')' 
             + ' FOR ' + QUOTENAME(@ColumnName)

    PRINT @Sql    
    
    FETCH NEXT FROM cur
     INTO @SchemaName, @TableName, @ColumnName, @ColumnType
END

CLOSE cur
DEALLOCATE cur