problem in fetching specific records from table

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SQL-Server-2008

Hi,
I am fetching top 10 records from particular table. In my application if user want some specific record to be fetched so I want output that specific record also but only 10 record should be fetched including that specific.

Eg. suppose I want 2 records which are not in top 10 but that 2 records also come including top 8 so total will be 10.

Posted 20-Dec-12 0:11am

Avinash_Pathak

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Jibesh 20-Dec-12 6:59am

is the 2 specific records comes through the sql query result? check your query condition you may have written to include the specific record too. you may use 'NOT IN' or 'NOT EXISTS' clause in your query to discard the specific record inclusion in the normal query.

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Arunprasath Natarajan · Answer 1 · 2012-12-20T00:25:00

Solution 1

Try this idea, Hope it helps you.
First load the data into DataTable_1. (Top 10)
Then User details into DataTable_2. (User Required Data)
Now merge the DataTable_1 and DataTable_2 using union.
Then Select Top 10.
Make sure that DataTable_2 records are loaded first.
It is simple.

Posted 20-Dec-12 0:25am

Arunprasath Natarajan

Comments

Avinash_Pathak 20-Dec-12 23:29pm

your idea is working but if i dont want to use union because its performance effective...is that any alternative??

__TR__ · Answer 2 · 2012-12-20T02:25:00

I am not sure why would you want to fetch records that were not requested by user, but here is one approach to your problem
Lets consider a sample table with a list of random names

SQL

DECLARE @Sample TABLE
(
	ID INT IDENTITY(1,1) PRIMARY KEY,
	SampleText VARCHAR(50)
)

INSERT INTO @Sample
SELECT 'abc' UNION ALL
SELECT 'abc1' UNION ALL
SELECT 'abc2' UNION ALL
SELECT 'abc3' UNION ALL
SELECT 'abc4' UNION ALL
SELECT 'xyz' UNION ALL
SELECT 'xyz1' UNION ALL
SELECT 'xyz2' UNION ALL
SELECT 'xyz3' UNION ALL
SELECT 'efg' UNION ALL
SELECT 'pqr' UNION ALL
SELECT 'mno' UNION ALL
SELECT 'efg' UNION ALL
SELECT 'sfr' UNION ALL
SELECT 'qwd' UNION ALL
SELECT 'gte' UNION ALL
SELECT 'sdf' UNION ALL
SELECT 'gtg' UNION ALL
SELECT 'sde'

Lets assume user requested for records that start with abc. First thing to do is to find the number of records that match this criteria.

SQL

DECLARE @Count INT
SELECT @Count = COUNT(*) FROM @Sample WHERE SampleText LIKE 'abc%'

Next get all the records that match the criteria and if the number of records matching the criteria is less than 10 then fetch other records (which don't match the user's criteria) so total records retrieved is 10.

SQL

SELECT TOP 10 * FROM @Sample WHERE SampleText LIKE 'abc%'
UNION ALL
SELECT TOP (10 - CASE WHEN @Count > 10 THEN 10 ELSE @Count END) *  FROM @Sample WHERE ID NOT IN (SELECT ID FROM @Sample WHERE SampleText LIKE 'abc%')