UPDATE table field based on SELECT statement

Hi Experts, please assist here; I am trying to UPDATE a field in a source table from the result of a calculated field (Step 5)

In SQL, I want to say
 UPDATE #SourceTable SET IsDuplicate = IsDuplicate from query in Step 5

Included below are queries to create and populate the tables to match my real table.

Thanks!!

-- STEP 1. This is the source table with property records.
CREATE TABLE #SourceTable(
      ID int IDENTITY
      ,CountyNumber int NULL
      ,PropertyAddress varchar(150) NULL
      ,City varchar(50) NULL
      ,State varchar (50) NULL
      ,DataSource int NULL
      ,PropertyTypeKey int NULL
      ,IsDuplicate bit NULL
      )

-- STEP 2: insert sample data
INSERT INTO #SourceTable(CountyNumber, PropertyAddress, City, State, DataSource, PropertyTypeKey)
      VALUES(123445, '1201 Startel Blvd', 'Phoenix', 'AZ', 2, 34)
                  ,(230087,'1234 Lakeview Terrace', 'Fargo', 'ND', 2, 45)
                  ,(234567,'1234 Lakeview Terrace', 'Fargo', 'ND', 3, 45)
                  ,(435678, '1234 Lakeview Terrace', 'Fargo', 'ND', 4, 45)
                  ,(567890, '167 Manatee Court', 'Provo', 'UT',5, 22)

---STEP 3: split the source data and populate the dependent tables
SELECT ID, CountyNumber, PropertyAddress, City, State INTO #DimProperty FROM #SourceTable
SELECT ID, CountyNumber, DataSource, PropertyTypeKey INTO #FactProperty FROM #SourceTable

-- STEP 4: confirm the records are correctly entered.
SELECT * FROM  #SourceTable
SELECT * FROM #DimProperty
SELECT * FROM #FactProperty

/*
STEP 5: this query checks for duplicate entries and marks the non-county records as 1 (Is Duplicate). It works as expected
 Reqirement is to update the value of IsDuplicate in the #SourceTable (#SourceTable.IsDuplicate) to match the value of "IsDuplicate" in this query
*/

SELECT DISTINCT dlis.CountyNumber, dlis.PropertyAddress, dlis.City, f.PropertyTypeKey
,CASE f.DataSource
            WHEN 2 THEN 'County Records'
            WHEN 3 THEN 'Archives'
            WHEN 4 THEN 'Owner Provided'
            WHEN 5 THEN 'Owner & State Info'
            ELSE 'Unknown'
      END AS 'DataSource'
      ,CASE
            WHEN ( f.DataSource != 2 ) THEN 1            
       END AS 'IsDuplicate'
 FROM (
       SELECT PropertyAddress, City      ,COUNT(PropertyAddress + ' ' + City) 'Count'
            FROM #SourceTable t
            GROUP BY PropertyAddress, City
            HAVING COUNT(PropertyAddress + ' ' + City) > 1 ) result
            JOIN #DimProperty dlis WITH (NOLOCK)
ON result.PropertyAddress = dlis.PropertyAddress
      JOIN #FactProperty f
ON dlis.ID = f.ID
            WHERE (DataSource IN (2, 3) OR DataSource IN (2, 4) OR DataSource IN (2, 5) )             
ORDER BY PropertyAddress


 --DROP TABLE #DimProperty
 --DROP TABLE #FactProperty
 --DROP TABLE #SourceTable
godwineffiongAsked:
Who is Participating?
 
godwineffiongConnect With a Mentor Author Commented:
I figured it out.  Below is solution query:
 UPDATE #SourceTable
SET IsDuplicate = 1
WHERE PropertyAddress IN (
SELECT t.PropertyAddress FROM(
SELECT PropertyAddress, City,COUNT(PropertyAddress + ' ' + City) 'Count'
FROM #SourceTable
GROUP BY PropertyAddress, City
HAVING COUNT(PropertyAddress + ' ' + City) > 1
) t )
AND DataSource != 2
 
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godwineffiongAuthor Commented:
I should mention that the CountyNumber is not unique. Different properties from same or different counties can have the same CountyNumber.
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Anthony PerkinsCommented:
I suspect you may find this a lot more efficient:
UPDATE	t
SET	IsDuplicate = 1
FROM	#SourceTable t
	INNER JOIN (
		SELECT	PropertyAddress
		FROM	#SourceTable
		GROUP BY 
			PropertyAddress,
			City
		HAVING COUNT(*) > 1) d ON t.PropertyAddress = d.PropertyAddress
WHERE	t.DataSource != 2 

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