Drop all the tables, stored procedures, triggers, constraints and all the dependencies in one sql statement

 /* Drop all non-system stored procs */  

 DECLARE @name VARCHAR(128)  
 DECLARE @SQL VARCHAR(254)  
 SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'P' AND category = 0 ORDER BY [name])  
 WHILE @name is not null  
 BEGIN  
   SELECT @SQL = 'DROP PROCEDURE [dbo].[' + RTRIM(@name) +']'  
   EXEC (@SQL)  
   PRINT 'Dropped Procedure: ' + @name  
   SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'P' AND category = 0 AND [name] > @name ORDER BY [name])  
 END  
 GO  

 /* Drop all views */  

 DECLARE @name VARCHAR(128)  
 DECLARE @SQL VARCHAR(254)  
 SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'V' AND category = 0 ORDER BY [name])  
 WHILE @name IS NOT NULL  
 BEGIN  
   SELECT @SQL = 'DROP VIEW [dbo].[' + RTRIM(@name) +']'  
   EXEC (@SQL)  
   PRINT 'Dropped View: ' + @name  
   SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'V' AND category = 0 AND [name] > @name ORDER BY [name])  
 END  
 GO  
 /* Drop all functions */  

 DECLARE @name VARCHAR(128)  
 DECLARE @SQL VARCHAR(254)  
 SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] IN (N'FN', N'IF', N'TF', N'FS', N'FT') AND category = 0 ORDER BY [name])  
 WHILE @name IS NOT NULL  
 BEGIN  
   SELECT @SQL = 'DROP FUNCTION [dbo].[' + RTRIM(@name) +']'  
   EXEC (@SQL)  
   PRINT 'Dropped Function: ' + @name  
   SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] IN (N'FN', N'IF', N'TF', N'FS', N'FT') AND category = 0 AND [name] > @name ORDER BY [name])  
 END  
 GO
  
 /* Drop all Foreign Key constraints */  

 DECLARE @name VARCHAR(128)  
 DECLARE @constraint VARCHAR(254)  
 DECLARE @SQL VARCHAR(254)  
 SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' ORDER BY TABLE_NAME)  
 WHILE @name is not null  
 BEGIN  
   SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)  
   WHILE @constraint IS NOT NULL  
   BEGIN  
     SELECT @SQL = 'ALTER TABLE [dbo].[' + RTRIM(@name) +'] DROP CONSTRAINT [' + RTRIM(@constraint) +']'  
     EXEC (@SQL)  
     PRINT 'Dropped FK Constraint: ' + @constraint + ' on ' + @name  
     SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' AND CONSTRAINT_NAME <> @constraint AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)  
   END  
 SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'FOREIGN KEY' ORDER BY TABLE_NAME)  
 END  
 GO  

 /* Drop all Primary Key constraints */  

 DECLARE @name VARCHAR(128)  
 DECLARE @constraint VARCHAR(254)  
 DECLARE @SQL VARCHAR(254)  
 SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' ORDER BY TABLE_NAME)  
 WHILE @name IS NOT NULL  
 BEGIN  
   SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)  
   WHILE @constraint is not null  
   BEGIN  
     SELECT @SQL = 'ALTER TABLE [dbo].[' + RTRIM(@name) +'] DROP CONSTRAINT [' + RTRIM(@constraint)+']'  
     EXEC (@SQL)  
     PRINT 'Dropped PK Constraint: ' + @constraint + ' on ' + @name  
     SELECT @constraint = (SELECT TOP 1 CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' AND CONSTRAINT_NAME <> @constraint AND TABLE_NAME = @name ORDER BY CONSTRAINT_NAME)  
   END  
 SELECT @name = (SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE constraint_catalog=DB_NAME() AND CONSTRAINT_TYPE = 'PRIMARY KEY' ORDER BY TABLE_NAME)  
 END  
 GO  

 /* Drop all tables */  

 DECLARE @name VARCHAR(128)  
 DECLARE @SQL VARCHAR(254)  
 SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'U' AND category = 0 ORDER BY [name])  
 WHILE @name IS NOT NULL  
 BEGIN  
   SELECT @SQL = 'DROP TABLE [dbo].[' + RTRIM(@name) +']'  
   EXEC (@SQL)  
   PRINT 'Dropped Table: ' + @name  
   SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'U' AND category = 0 AND [name] > @name ORDER BY [name])  
 END  
 GO