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sql delete

Posted on 2013-05-16
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Last Modified: 2013-06-10
I need to be able to delete a contents of a column but only if it is over 50 weeks old I have the 50 weeks on bit but not sure how to remove contents from it
     (Crtd BETWEEN CAST(CAST(DATEADD(week, - 50, GETDATE()) AS date) AS datetime) AND DATEADD(second, - 1, DATEADD(day, 1, CAST(CAST(DATEADD(week, 
                         - 51, GETDATE()) AS date) AS datetime))))

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Question by:beridius
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4 Comments
 
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Accepted Solution

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Ross Turner earned 500 total points
ID: 39171165
You just update the column fields to null using your where

Update youtable 
set yourcolumn = null 
where  (Crtd BETWEEN CAST(CAST(DATEADD(week, - 50, GETDATE()) AS date) AS datetime) AND DATEADD(second, - 1, DATEADD(day, 1, CAST(CAST(DATEADD(week, 
                         - 51, GETDATE()) AS date) AS datetime))))

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Expert Comment

by:Jim Horn
ID: 39171169
The term DELETE refers to entire rows, not the contents of a column.  
It's an UPDATE to delete contents of a column...

UPDATE YourTable
SET a_column = NULL
WHERE {the 50 weeks on bit}
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LVL 7

Expert Comment

by:Ross Turner
ID: 39171242
Hi Beridius

i've create this example for you

http://sqlfiddle.com/#!3/17028/4

Create table test 
(
 VALID_FROM varchar (30),
 VALID_TO varchar (30),
 TXT varchar (30)
)

INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-06-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-06-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-06-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-05-14 00:00:00.000','2012-11-13 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-05-14 00:00:00.000','2012-11-13 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-03-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-06-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-04-01 00:00:00.000','2013-04-01 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-04-01 00:00:00.000','2013-04-01 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-03-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-03-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2012-07-01 00:00:00.000','2013-06-30 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-05-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-05-01 00:00:00.000','2013-05-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-04-01 00:00:00.000','2013-06-30 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-04-01 00:00:00.000','2014-03-31 00:00:00.000','Test')
INSERT INTO test(VALID_FROM,VALID_TO,txt) VALUES('2013-04-01 00:00:00.000','2014-03-31 00:00:00.000','Test')

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-- Select 

Select
VALID_FROM,
VALID_TO ,
TXT,
DATEDIFF(week,cast([VALID_FROM] as datetime),cast([VALID_TO]as datetime)) AS DiffDate
from test;

-- Update 

update test
set txt = null
where DATEDIFF(week,cast([VALID_FROM] as datetime),cast([VALID_TO]as datetime)) > 51;

-- Select 

Select
VALID_FROM,
VALID_TO ,
TXT,
DATEDIFF(week,cast([VALID_FROM] as datetime),cast([VALID_TO]as datetime)) AS DiffDate
from test;

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Author Comment

by:beridius
ID: 39171390
I will give this a try thanks guys
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