SQL Reloaded: Preparing test data

    There are cases in which we need to create test data in order to check a certain functionality. In this post I'll show how can be created data with the help of loops. For this let's create a simple table containing 5 fields: 

-- creating the test table 
CREATE TABLE Table1( 
ID int NOT NULL 
, [Year] int NOT NULL 
, Product varchar(30) NOT NULL 
, Price decimal(13,2) NOT NULL 
, Quantity decimal(13,3) NOT NULL) 

-- dropping the test table 
--DROP TABLE Table1 

-- deleting the data 
--TRUNCATE TABLE Table1          

        

Usually I'm commenting DROP and TRUNCATES so I can avoid the modification of data by mistake.

 And now the loop, with the help of RAND and modulo the values can be varied:

-- inserting the data
DECLARE @index int 
SET @index = 1 
WHILE @index < 99
BEGIN 
      INSERT Table1(ID, [Year], Product, Price, Quantity) 
      VALUES (@index, 2000 + (@index % 4), 'Product ' + Cast(@index%10 as char(3)), 10 * RAND(), 100 * RAND()) SET @index = @index + 1 
END 


--testing the output 
SELECT * 
FROM Table1     

-- using the data
SELECT [Year], Product, SUM(Price * Quantity) Amount 
FROM Table1 
GROUP BY [Year], Product
ORDER BY [Year], Product