Question

should be simple enough but it’s causing me a couple of issues.

I have a data set similar to the following:

User   UserID   Name   Age  UserPropertyValues   UserID   PropertyCodeValueID  PropertyCodes   PropertyCodeID   PropertyCodeName  PropertyCodeValues   PropertyCodeValueID   PropertyCodeID   PropertValue 

Now let’s assume the tables contain the following data:

1  John  25 2  Sarah  34  1  2 1  3 2  1 2  3  1  FavColour 2  CarMake 3  PhoneType  1  1  Blue 2  1  Yellow 3  2  Ford 4  3  Mobile 5  3  Landline 

Now from this I’m looking to create a view to return the User details, as well as the property values for Property code 1 and 2 like so:

John 25 Yellow Ford Sarah 34 Blue Ford 

The queries I have tried so far tend to return repeating rows of data :

John 25 Yellow John 25 Ford Sarah 34 Blue Sarah 34 Ford 

Any help is appreciated, thank you all in advance.

Answer 1

Input data:

DECLARE @User TABLE (UserID INT, Name VARCHAR(10), Age INT) INSERT INTO @User SELECT 1,  'John',  25 UNION SELECT 2,  'Sarah',  34 DECLARE @UserPropertyValues TABLE(UserID INT, PropertyCodeValueID INT) INSERT INTO @UserPropertyValues SELECT 1, 2 UNION SELECT 1, 3 UNION SELECT 2, 1 UNION SELECT 2,  3 DECLARE @PropertyCodes    TABLE (PropertyCodeID INT, PropertyCodeName VARCHAR(10)) INSERT INTO @PropertyCodes SELECT 1,  'FavColour' UNION SELECT 2,  'CarMake' UNION SELECT 3,  'PhoneType' DECLARE @PropertyCodeValues TABLE (PropertyCodeValueID INT,    PropertyCodeID INT, PropertValue VARCHAR(10)) INSERT INTO @PropertyCodeValues SELECT 1,  1,  'Blue' UNION SELECT 2,  1,  'Yellow' UNION SELECT 3,  2,  'Ford' UNION SELECT 4,  3,  'Mobile' UNION SELECT 5,  3,  'Landline' 

If two properties is all that you need in result, and each user have those properties, then try this:

SELECT U.Name, U.Age, PCVFC.PropertValue, PCVCM.PropertValue  FROM @User U INNER JOIN @UserPropertyValues UPVFC ON U.UserID = UPVFC.UserID  INNER JOIN @PropertyCodeValues PCVFC    ON UPVFC.PropertyCodeValueID = PCVFC.PropertyCodeValueID      AND PCVFC.PropertyCodeID = 1 INNER JOIN @UserPropertyValues UPVCM ON U.UserID = UPVCM.UserID  INNER JOIN @PropertyCodeValues PCVCM    ON UPVCM.PropertyCodeValueID = PCVCM.PropertyCodeValueID      AND PCVCM.PropertyCodeID = 2 

[edit] But to handle possible NULL values better use this:

SELECT U.Name, U.Age, FC.PropertValue, CM.PropertValue  FROM @User U LEFT JOIN (   SELECT UserID, PropertValue FROM @UserPropertyValues  UPV     INNER JOIN @PropertyCodeValues PCV        ON UPV.PropertyCodeValueID = PCV.PropertyCodeValueID          AND PCV.PropertyCodeID = 1 ) FC ON U.UserID = FC.UserID LEFT JOIN (   SELECT UserID, PropertValue FROM @UserPropertyValues  UPV     INNER JOIN @PropertyCodeValues PCV        ON UPV.PropertyCodeValueID = PCV.PropertyCodeValueID          AND PCV.PropertyCodeID = 2 ) CM ON U.UserID = CM.UserID