How can I delete duplicate rows where no unique row id exists?
My table is
col1 col2 col3 col4 col5 col6 col7
john 1 1 1 1 1 1
john 1 1 1 1 1 1
sally 2 2 2 2 2 2
sally 2 2 2 2 2 2
I want to be left with the following after the duplicate removal:
john 1 1 1 1 1 1
sally 2 2 2 2 2 2
I've tried a few queries but I think they depend on having a row id as I don't get the desired result. For example:
DELETE
FROM table
WHERE col1 IN (
SELECT id
FROM table
GROUP BY id
HAVING (COUNT(col1) > 1)
)
I like CTEs and ROW_NUMBER as the two combined allow us to see which rows are deleted (or updated), therefore just change the DELETE FROM CTE... to SELECT * FROM CTE:
WITH CTE AS(
SELECT [col1], [col2], [col3], [col4], [col5], [col6], [col7],
RN = ROW_NUMBER()OVER(PARTITION BY col1 ORDER BY col1)
FROM dbo.Table1
)
DELETE FROM CTE WHERE RN > 1
DEMO (result is different; I assume that it's due to a typo on your part)
COL1 COL2 COL3 COL4 COL5 COL6 COL7
john 1 1 1 1 1 1
sally 2 2 2 2 2 2
This example determines duplicates by a single column col1 because of the PARTITION BY col1. If you want to include multiple columns simply add them to the PARTITION BY:
ROW_NUMBER()OVER(PARTITION BY Col1, Col2, ... ORDER BY OrderColumn)
I would prefer CTE for deleting duplicate rows from sql server table
strongly recommend to follow this article ::http://codaffection.com/sql-server-article/delete-duplicate-rows-in-sql-server/
by keeping original
WITH CTE AS
(
SELECT *,ROW_NUMBER() OVER (PARTITION BY col1,col2,col3 ORDER BY col1,col2,col3) AS RN
FROM MyTable
)
DELETE FROM CTE WHERE RN<>1
without keeping original
WITH CTE AS
(SELECT *,R=RANK() OVER (ORDER BY col1,col2,col3)
FROM MyTable)
DELETE CTE
WHERE R IN (SELECT R FROM CTE GROUP BY R HAVING COUNT(*)>1)
Without using CTE and ROW_NUMBER() you can just delete the records just by using group by with MAX function here is an example
DELETE
FROM MyDuplicateTable
WHERE ID NOT IN
(
SELECT MAX(ID)
FROM MyDuplicateTable
GROUP BY DuplicateColumn1, DuplicateColumn2, DuplicateColumn3)
If you have no references, like foreign keys, you can do this. I do it a lot when testing proofs of concept and the test data gets duplicated.
SELECT DISTINCT [col1],[col2],[col3],[col4],[col5],[col6],[col7]
INTO [newTable]
FROM [oldTable]
Go into the object explorer and delete the old table.
Rename the new table with the old table's name.
Remove all duplicates, but the very first ones (with min ID)
should work equally in other SQL servers, like Postgres:
DELETE FROM table
WHERE id NOT IN (
select min(id) from table
group by col1, col2, col3, col4, col5, col6, col7
)
DELETE from search
where id not in (
select min(id) from search
group by url
having count(*)=1
union
SELECT min(id) FROM search
group by url
having count(*) > 1
)
There are two solutions in mysql:
A) Delete duplicate rows using DELETE JOIN statement
DELETE t1 FROM contacts t1
INNER JOIN contacts t2
WHERE
t1.id < t2.id AND
t1.email = t2.email;
This query references the contacts table twice, therefore, it uses the table alias t1 and t2.
The output is:
1
Query OK, 4 rows affected (0.10 sec)
In case you want to delete duplicate rows and keep the lowest id, you can use the following statement:
DELETE c1 FROM contacts c1
INNER JOIN contacts c2
WHERE
c1.id > c2.id AND
c1.email = c2.email;
B) Delete duplicate rows using an intermediate table
The following shows the steps for removing duplicate rows using an intermediate table:
1. Create a new table with the structure the same as the original table that you want to delete duplicate rows.
2. Insert distinct rows from the original table to the immediate table.
3. Insert distinct rows from the original table to the immediate table.
Step 1. Create a new table whose structure is the same as the original table:
CREATE TABLE source_copy LIKE source;
Step 2. Insert distinct rows from the original table to the new table:
INSERT INTO source_copy
SELECT * FROM source
GROUP BY col; -- column that has duplicate values
Step 3. drop the original table and rename the immediate table to the original one
DROP TABLE source;
ALTER TABLE source_copy RENAME TO source;
Source: http://www.mysqltutorial.org/mysql-delete-duplicate-rows/
Please see the below way of deletion too.
Declare #table table
(col1 varchar(10),col2 int,col3 int, col4 int, col5 int, col6 int, col7 int)
Insert into #table values
('john',1,1,1,1,1,1),
('john',1,1,1,1,1,1),
('sally',2,2,2,2,2,2),
('sally',2,2,2,2,2,2)
Created a sample table named #table and loaded it with given data.
Delete aliasName from (
Select *,
ROW_NUMBER() over (Partition by col1,col2,col3,col4,col5,col6,col7 order by col1) as rowNumber
From #table) aliasName
Where rowNumber > 1
Select * from #table
Note: If you are giving all columns in the Partition by part, then order by do not have much significance.
I know, the question is asked three years ago, and my answer is another version of what Tim has posted, But posting just incase it is helpful for anyone.
It can be done by many ways in sql server
the most simplest way to do so is:
Insert the distinct rows from the duplicate rows table to new temporary table. Then delete all the data from duplicate rows table then insert all data from temporary table which has no duplicates as shown below.
select distinct * into #tmp From table
delete from table
insert into table
select * from #tmp drop table #tmp
select * from table
Delete duplicate rows using Common Table Expression(CTE)
With CTE_Duplicates as
(select id,name , row_number()
over(partition by id,name order by id,name ) rownumber from table )
delete from CTE_Duplicates where rownumber!=1
To delete the duplicate rows from the table in SQL Server, you follow these steps:
Find duplicate rows using GROUP BY clause or ROW_NUMBER() function.
Use DELETE statement to remove the duplicate rows.
Setting up a sample table
DROP TABLE IF EXISTS contacts;
CREATE TABLE contacts(
contact_id INT IDENTITY(1,1) PRIMARY KEY,
first_name NVARCHAR(100) NOT NULL,
last_name NVARCHAR(100) NOT NULL,
email NVARCHAR(255) NOT NULL,
);
Insert values
INSERT INTO contacts
(first_name,last_name,email)
VALUES
('Syed','Abbas','syed.abbas#example.com'),
('Catherine','Abel','catherine.abel#example.com'),
('Kim','Abercrombie','kim.abercrombie#example.com'),
('Kim','Abercrombie','kim.abercrombie#example.com'),
('Kim','Abercrombie','kim.abercrombie#example.com'),
('Hazem','Abolrous','hazem.abolrous#example.com'),
('Hazem','Abolrous','hazem.abolrous#example.com'),
('Humberto','Acevedo','humberto.acevedo#example.com'),
('Humberto','Acevedo','humberto.acevedo#example.com'),
('Pilar','Ackerman','pilar.ackerman#example.com');
Query
SELECT
contact_id,
first_name,
last_name,
email
FROM
contacts;
Delete duplicate rows from a table
WITH cte AS (
SELECT
contact_id,
first_name,
last_name,
email,
ROW_NUMBER() OVER (
PARTITION BY
first_name,
last_name,
email
ORDER BY
first_name,
last_name,
email
) row_num
FROM
contacts
)
DELETE FROM cte
WHERE row_num > 1;
Should delete the record now
Try to Use:
SELECT linkorder
,Row_Number() OVER (
PARTITION BY linkorder ORDER BY linkorder DESC
) AS RowNum
FROM u_links
Microsoft has a vey ry neat guide on how to remove duplicates. Check out http://support.microsoft.com/kb/139444
In brief, here is the easiest way to delete duplicates when you have just a few rows to delete:
SET rowcount 1;
DELETE FROM t1 WHERE myprimarykey=1;
myprimarykey is the identifier for the row.
I set rowcount to 1 because I only had two rows that were duplicated. If I had had 3 rows duplicated then I would have set rowcount to 2 so that it deletes the first two that it sees and only leaves one in table t1.
with myCTE
as
(
select productName,ROW_NUMBER() over(PARTITION BY productName order by slno) as Duplicate from productDetails
)
Delete from myCTE where Duplicate>1
After trying the suggested solution above, that works for small medium tables.
I can suggest that solution for very large tables. since it runs in iterations.
Drop all dependency views of the LargeSourceTable
you can find the dependecies by using sql managment studio, right click on the table and click "View Dependencies"
Rename the table:
sp_rename 'LargeSourceTable', 'LargeSourceTable_Temp'; GO
Create the LargeSourceTable again, but now, add a primary key with all the columns that define the duplications add WITH (IGNORE_DUP_KEY = ON)
For example:
CREATE TABLE [dbo].[LargeSourceTable]
(
ID int IDENTITY(1,1),
[CreateDate] DATETIME CONSTRAINT [DF_LargeSourceTable_CreateDate] DEFAULT (getdate()) NOT NULL,
[Column1] CHAR (36) NOT NULL,
[Column2] NVARCHAR (100) NOT NULL,
[Column3] CHAR (36) NOT NULL,
PRIMARY KEY (Column1, Column2) WITH (IGNORE_DUP_KEY = ON)
);
GO
Create again the views that you dropped in the first place for the new created table
Now, Run the following sql script, you will see the results in 1,000,000 rows per page, you can change the row number per page to see the results more often.
Note, that I set the IDENTITY_INSERT on and off because one the columns contains auto incremental id, which I'm also copying
SET IDENTITY_INSERT LargeSourceTable ON
DECLARE #PageNumber AS INT, #RowspPage AS INT
DECLARE #TotalRows AS INT
declare #dt varchar(19)
SET #PageNumber = 0
SET #RowspPage = 1000000
select #TotalRows = count (*) from LargeSourceTable_TEMP
While ((#PageNumber - 1) * #RowspPage < #TotalRows )
Begin
begin transaction tran_inner
; with cte as
(
SELECT * FROM LargeSourceTable_TEMP ORDER BY ID
OFFSET ((#PageNumber) * #RowspPage) ROWS
FETCH NEXT #RowspPage ROWS ONLY
)
INSERT INTO LargeSourceTable
(
ID
,[CreateDate]
,[Column1]
,[Column2]
,[Column3]
)
select
ID
,[CreateDate]
,[Column1]
,[Column2]
,[Column3]
from cte
commit transaction tran_inner
PRINT 'Page: ' + convert(varchar(10), #PageNumber)
PRINT 'Transfered: ' + convert(varchar(20), #PageNumber * #RowspPage)
PRINT 'Of: ' + convert(varchar(20), #TotalRows)
SELECT #dt = convert(varchar(19), getdate(), 121)
RAISERROR('Inserted on: %s', 0, 1, #dt) WITH NOWAIT
SET #PageNumber = #PageNumber + 1
End
SET IDENTITY_INSERT LargeSourceTable OFF
-- this query will keep only one instance of a duplicate record.
;WITH cte
AS (SELECT ROW_NUMBER() OVER (PARTITION BY col1, col2, col3-- based on what? --can be multiple columns
ORDER BY ( SELECT 0)) RN
FROM Mytable)
delete FROM cte
WHERE RN > 1
You need to group by the duplicate records according to the field(s), then hold one of the records and delete the rest.
For example:
DELETE prg.Person WHERE Id IN (
SELECT dublicateRow.Id FROM
(
select MIN(Id) MinId, NationalCode
from prg.Person group by NationalCode having count(NationalCode ) > 1
) GroupSelect
JOIN prg.Person dublicateRow ON dublicateRow.NationalCode = GroupSelect.NationalCode
WHERE dublicateRow.Id <> GroupSelect.MinId)
Deleting duplicates from a huge(several millions of records) table might take long time . I suggest that you do a bulk insert into a temp table of the selected rows rather than deleting.
--REWRITING YOUR CODE(TAKE NOTE OF THE 3RD LINE) WITH CTE AS(SELECT NAME,ROW_NUMBER()
OVER (PARTITION BY NAME ORDER BY NAME) ID FROM #TB) SELECT * INTO #unique_records FROM
CTE WHERE ID =1;
This might help in your case
DELETE t1 FROM table t1 INNER JOIN table t2 WHERE t1.id > t2.id AND t1.col1 = t2.col1
With reference to https://support.microsoft.com/en-us/help/139444/how-to-remove-duplicate-rows-from-a-table-in-sql-server
The idea of removing duplicate involves
a) Protecting those rows that are not duplicate
b) Retain one of the many rows that qualified together as duplicate.
Step-by-step
1) First identify the rows those satisfy the definition of duplicate
and insert them into temp table, say #tableAll .
2) Select non-duplicate(single-rows) or distinct rows into temp table
say #tableUnique.
3) Delete from source table joining #tableAll to delete the
duplicates.
4) Insert into source table all the rows from #tableUnique.
5) Drop #tableAll and #tableUnique
If you have the ability to add a column to the table temporarily, this was a solution that worked for me:
ALTER TABLE dbo.DUPPEDTABLE ADD RowID INT NOT NULL IDENTITY(1,1)
Then perform a DELETE using a combination of MIN and GROUP BY
DELETE b
FROM dbo.DUPPEDTABLE b
WHERE b.RowID NOT IN (
SELECT MIN(RowID) AS RowID
FROM dbo.DUPPEDTABLE a WITH (NOLOCK)
GROUP BY a.ITEM_NUMBER,
a.CHARACTERISTIC,
a.INTVALUE,
a.FLOATVALUE,
a.STRINGVALUE
);
Verify that the DELETE performed correctly:
SELECT a.ITEM_NUMBER,
a.CHARACTERISTIC,
a.INTVALUE,
a.FLOATVALUE,
a.STRINGVALUE, COUNT(*)--MIN(RowID) AS RowID
FROM dbo.DUPPEDTABLE a WITH (NOLOCK)
GROUP BY a.ITEM_NUMBER,
a.CHARACTERISTIC,
a.INTVALUE,
a.FLOATVALUE,
a.STRINGVALUE
ORDER BY COUNT(*) DESC
The result should have no rows with a count greater than 1. Finally, remove the rowid column:
ALTER TABLE dbo.DUPPEDTABLE DROP COLUMN RowID;
Oh wow, i feel so stupid by ready all this answers, they are like experts' answer with all CTE and temp table and etc.
And all I did to get it working was simply aggregated the ID column by using MAX.
DELETE FROM table WHERE col1 IN (
SELECT MAX(id) FROM table GROUP BY id HAVING ( COUNT(col1) > 1 )
)
NOTE: you might need to run it multiple time to remove duplicate as this will only delete one set of duplicate rows at a time.
please simply add the keyword DISTINCT right after the SELECT command,
for example:
SELECT DISTICNT ColumnOne, ColumnTwo, ColumnThree
FROM YourTable
Another way of removing dublicated rows without loosing information in one step is like following:
delete from dublicated_table t1 (nolock)
join (
select t2.dublicated_field
, min(len(t2.field_kept)) as min_field_kept
from dublicated_table t2 (nolock)
group by t2.dublicated_field having COUNT(*)>1
) t3
on t1.dublicated_field=t3.dublicated_field
and len(t1.field_kept)=t3.min_field_kept
DECLARE #TB TABLE(NAME VARCHAR(100));
INSERT INTO #TB VALUES ('Red'),('Red'),('Green'),('Blue'),('White'),('White')
--**Delete by Rank**
;WITH CTE AS(SELECT NAME,DENSE_RANK() OVER (PARTITION BY NAME ORDER BY NEWID()) ID FROM #TB)
DELETE FROM CTE WHERE ID>1
SELECT NAME FROM #TB;
--**Delete by Row Number**
;WITH CTE AS(SELECT NAME,ROW_NUMBER() OVER (PARTITION BY NAME ORDER BY NAME) ID FROM #TB)
DELETE FROM CTE WHERE ID>1;
SELECT NAME FROM #TB;
DELETE FROM TBL1 WHERE ID IN
(SELECT ID FROM TBL1 a WHERE ID!=
(select MAX(ID) from TBL1 where DUPVAL=a.DUPVAL
group by DUPVAL
having count(DUPVAL)>1))
DELETE p1 FROM Person p1,
Person p2
WHERE
p1.Email = p2.Email AND p1.Id > p2.Id
I need to select random rows from a table for test data. There may be times I need more rows of test data than there are records in the table. Duplicates are okay. How do I structure my select so that I can get duplicate rows?
CREATE TABLE [Northwind].[dbo].[Persons]
(PersonID int, LastName varchar(255))
INSERT INTO [Northwind].[dbo].[Persons]
VALUES
(1, 'Smith'),
(2, 'Jones'),
(3, 'Washington')
SELECT TOP 5 *
FROM [Northwind].[dbo].[Persons]
ORDER BY NEWID()
How do I get the Select statement to give me five records in random order, with repeats? Currently, it only returns three in random order.
I'd like to be able to extend this to get 100 rows or 1000 rows or however many I need.
Use a recursive CTE to union enough rows so that they are larger than what you desire. Then select from that as you have done before.
declare
#desired int = 5,
#actual int = (select count(*) from persons);
with
persons as (
select personId,
lastName,
batch = 0
from Persons
union all
select personId,
lastName,
batch = batch + 1
from persons
where (batch + 1) * #actual < #desired
)
select
top (#desired) personId, lastName
from persons
order by newid()
As mentioned. You could instead us a tally table and then get the random rows;
WITH N AS(
SELECT N
FROM (VALUES(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL)))N(N)),
Tally AS(
SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS I
FROM N N1, N N2, N N3, N N4) --Repeat for more
SELECT TOP 500 YT.*
FROM Tally T
CROSS JOIN YourTable YT
ORDER BY NEWID();
I was thinking of how you would solve this without ordering all the records, especially multiple times.
One method is to generate random numbers and to use those for looking up values in your data:
with n as (
select rand(checksum(newid())) as r, 1 as n
union all
select rand(checksum(newid())) as r, n + 1
from n
where n < 10
),
tt as (
select t.*, lag(tile_end, 1, 0) over (order by tile_end) as tile_start
from (select t.*, row_number() over (order by newid()) * 1.0 / count(*) over () as tile_end
from t
) t
)
select tt.*, n.r, (select count(*) from n)
from n left join
tt
on n.r >= tt.tile_start and n.r < tt.tile_end;
Here is a db<>fiddle. The row_number() does not need to use order by newid(). It can order by a key that has an index -- which makes that component much more efficient.
For more than 100 rows, you will need OPTION (MAXRECURSION 0).
I added a temp results table and looped through the query and pushed the results into the temp table.
declare #results table(
SSN varchar(10),
Cusip varchar(10),
...
EndBillingDate varchar(10))
DECLARE #cnt INT = 0;
WHILE #cnt < #trades
BEGIN
INSERT INTO #results
Select ...
set #cnt = #cnt + 10
END
select * from #results
I'm using SQL Server 2005 and I'm trying to achieve something like this:
I want to get the first x rows and the last x rows in the same select statement.
SELECT TOP(5) BOTTOM(5)
Of course BOTTOM does not exist, so I need another solution. I believe there is an easy and elegant solution that I'm not getting. Doing the select again with GROUP BY DESC is not an option.
Using a union is the only thing I can think of to accomplish this
select * from (select top(5) * from logins order by USERNAME ASC) a
union
select * from (select top(5) * from logins order by USERNAME DESC) b
Check the link
SQL SERVER – How to Retrieve TOP and BOTTOM Rows Together using T-SQL
Did you try to using rownumber?
SELECT *
FROM
(SELECT *, ROW_NUMBER() OVER (Order BY columnName) as TopFive
,ROW_NUMBER() OVER (Order BY columnName Desc) as BottomFive
FROM Table
)
WHERE TopFive <=5 or BottomFive <=5
http://www.sqlservercurry.com/2009/02/select-top-n-and-bottom-n-rows-using.html
I think you've two main options:
SELECT TOP 5 ...
FROM ...
ORDER BY ... ASC
UNION
SELECT TOP 5 ...
FROM ...
ORDER BY ... DESC
Or, if you know how many items there are in the table:
SELECT ...
FROM (
SELECT ..., ROW_NUMBER() OVER (ORDER BY ... ASC) AS intRow
FROM ...
) AS T
WHERE intRow BETWEEN 1 AND 5 OR intRow BETWEEN #Number - 5 AND #Number
Is it an option for you to use a union?
E.g.
select top 5 ... order by {specify columns asc}
union
select top 5 ... order by {specify columns desc}
i guess you have to do it using subquery only
select * from table where id in (
(SELECT id ORDER BY columnName LIMIT 5) OR
(SELECT id ORDER BY columnName DESC LIMIT 5)
)
select * from table where id in (
(SELECT TOP(5) id ORDER BY columnName) OR
(SELECT TOP(5) id ORDER BY columnName DESC)
)
EDITED
select * from table where id in (
(SELECT TOP 5 id ORDER BY columnName) OR
(SELECT TOP 5 id ORDER BY columnName DESC)
)
No real difference between this and the union that I'm aware of, but technically it is a single query.
select t.*
from table t
where t.id in (select top 5 t2.id from table t2 order by MyColumn)
or
t.id in (select top 5 t2.id from table t2 order by MyColumn desc);
SELECT *
FROM (
SELECT x, rank() over (order by x asc) as rown
FROM table
) temp
where temp.rown = 1
or temp.rown = (select count(x) from table)
Then you are out - doing the select again IS the only option, unless you want to pull in the complete result set and then throwing away everything in between.
ANY sql I cna think of is the same way - for the bottom you need to know first either how many items you have (materialize everything or use count(*)) or a reverse sort order.
Sorry if that does not suit you, but at the end.... reality does not care, and I do not see any other way to do that.
I had to do this recently for a very large stored procedure; if your query is quite large, and you want to minimize the amount of queries you could declare a #tempTable, insert into that #tempTable then query from that #tempTable,
DECLARE #tempTable TABLE ( columns.. )
INSERT INTO #tempTable
VALUES ( SELECT.. your query here ..)
SELECT TOP(5) columns FROM #tempTable ORDER BY column ASC -- returns first to last
SELECT TOP(5) columns FROM #tempTable ORDER BY column DESC -- returns last to first
In Microsoft SQL Server 2005 or above, I would like to get the first row, and if there is no matching row, then return a row with default values.
SELECT TOP 1 ID,Name
FROM TableName
UNION ALL
SELECT 0,''
ORDER BY ID DESC
This works, except that it returns two rows if there is data in the table, and 1 row if not.
I'd like it to always return 1 row.
I think it has something to do with EXISTS, but I'm not sure.
It would be something like:
SELECT TOP 1 * FROM Contact
WHERE EXISTS(select * from contact)
But if not EXISTS, then SELECT 0,''
What happens when the table is very full and you might want to specify which row of your top 1 to get, such as the first name? OMG Ponies' query will return the wrong answer in that case if you just change the ORDER BY clause. His query also costs about 8% more CPU than this modification (though it has equal reads)
SELECT TOP 1 *
FROM (
SELECT TOP 1 ID,Name
FROM TableName
ORDER BY Name
UNION ALL
SELECT 0,''
) X
ORDER BY ID DESC
The difference is that the inner query has a TOP 1 also, and which TOP 1 can be specified there (as shown).
Just for fun, this is another way to do it which performs very closely to the above query (-15ms to +30ms). While it's more complicated than necessary for such a simple query, it demonstrates a technique that I don't see other SQL folks using very often.
SELECT
ID = Coalesce(T.ID, 0),
Name = Coalesce(T.Name, '')
FROM
(SELECT 1) X (Num)
LEFT JOIN (
SELECT TOP 1 ID, Name
FROM TableName
ORDER BY ID DESC
) T ON 1 = 1 -- effective cross join but does not limit rows in the first table
Use:
SELECT TOP 1
x.id,
x.name
FROM (SELECT t.id,
t.name
FROM TABLENAME t
UNION ALL
SELECT 0,
'') x
ORDER BY id DESC
Using a CTE equivalent:
WITH query AS (
SELECT t.id,
t.name
FROM TABLENAME t
UNION ALL
SELECT 0,
'')
SELECT TOP 1
x.id,
x.name
FROM query x
ORDER BY x.id DESC
CREATE TABLE #sample(id INT, data VARCHAR(10))
SELECT TOP 1 id, data INTO #temp FROM #sample
IF ##ROWCOUNT = 0 INSERT INTO #temp VALUES (null, null)
SELECT * FROM #temp
put the top oustide of the UNION query
SELECT TOP 1 * FROM(
SELECT ID,Name
FROM TableName
UNION ALL
SELECT 0,''
) z
ORDER BY ID DESC
IF EXISTS ( SELECT TOP 1 ID, Name FROM TableName )
BEGIN
SELECT TOP 1 ID, Name FROM TableName
END
ELSE
BEGIN
--exists returned no rows
--send a default row
SELECT 0, ''
END