Clear many fields in a query

I have a table from which I want to clear all data in many fields, but not all fields.
The field types differ. Some are dates and some are strings. I will like to use an update query.
The table has 8400 records.
Or would you rather suggest I use code.
How should I do it? How do you update a date to "nothing"? And a string?
My select query looks as below.

SELECT TblBlocks.SampleDate, TblBlocks.TestDate, TblBlocks.Virus, TblBlocks.TestResult, TblBlocks.TestComment, TblBlocks.AM, TblBlocks.AMDate, TblBlocks.CommentAM, TblBlocks.AGC, TblBlocks.AGCDate, TblBlocks.CommentAGC, TblBlocks.AP, TblBlocks.APDate, TblBlocks.CommentAP, TblBlocks.AR, TblBlocks.ARDate, TblBlocks.CommentAR, TblBlocks.BC, TblBlocks.BCDate, TblBlocks.CF, TblBlocks.CFDate, TblBlocks.CommentCF, TblBlocks.CL, TblBlocks.CLDate, TblBlocks.CommentCL, TblBlocks.CR, TblBlocks.CRDate, TblBlocks.CommentCR, TblBlocks.FL, TblBlocks.FLDate, TblBlocks.CommentFL, TblBlocks.GCB, TblBlocks.GCBDate, TblBlocks.CommentGCB, TblBlocks.GD, TblBlocks.GDDAte, TblBlocks.CommentGD, TblBlocks.GF, TblBlocks.GFDate, TblBlocks.CommentGF, TblBlocks.GFL, TblBlocks.GFLDate, TblBlocks.CommentGFL, TblBlocks.GS, TblBlocks.GSDate, TblBlocks.CommentGS, TblBlocks.LP, TblBlocks.LPDate, TblBlocks.CommentLP, TblBlocks.LR, TblBlocks.LRDate, TblBlocks.CommentLR, TblBlocks.LRC, TblBlocks.LRCDate, TblBlocks.CommentLRC, TblBlocks.NS, TblBlocks.NSDate, TblBlocks.CommentNS, TblBlocks.PD, TblBlocks.PDDate, TblBlocks.CommentPD, TblBlocks.PL, TblBlocks.PLDate, TblBlocks.CommentPL, TblBlocks.PKRR, TblBlocks.PKRRDate, TblBlocks.CommentPKRR, TblBlocks.PKRV, TblBlocks.PKRVDate, TblBlocks.CommentPKRV, TblBlocks.PR, TblBlocks.PRDate, TblBlocks.CommentPR, TblBlocks.PRPM, TblBlocks.PRPMDate, TblBlocks.CommentPRPM, TblBlocks.PDW, TblBlocks.PDWDate, TblBlocks.CommentPDW, TblBlocks.QS, TblBlocks.QSDate, TblBlocks.CommentQS, TblBlocks.RL, TblBlocks.RLDate, TblBlocks.CommentRL, TblBlocks.RR, TblBlocks.RRDate, TblBlocks.CommentRR, TblBlocks.RW, TblBlocks.RWDate, TblBlocks.CommentRW, TblBlocks.SB, TblBlocks.SBDate, TblBlocks.CommentSB, TblBlocks.SD, TblBlocks.SDDate, TblBlocks.CommentSD, TblBlocks.SG, TblBlocks.SGDate, TblBlocks.CommentSG, TblBlocks.SP, TblBlocks.SPDate, TblBlocks.CommentSP, TblBlocks.SR, TblBlocks.SRDate, TblBlocks.CommentSR, TblBlocks.SS, TblBlocks.SSDate, TblBlocks.CommentSS, TblBlocks.TL, TblBlocks.TLDate, TblBlocks.CommentTL, TblBlocks.TP, TblBlocks.TPDate, TblBlocks.CommentTP, TblBlocks.VS, TblBlocks.VSDate, TblBlocks.CommentVS, TblBlocks.VY, TblBlocks.VYDate, TblBlocks.CommentVY, TblBlocks.YB, TblBlocks.YBDate, TblBlocks.CommentYB, TblBlocks.GVA, TblBlocks.GVADate, TblBlocks.CommentGVA, TblBlocks.GVB, TblBlocks.GVBDate, TblBlocks.CommentGVB, TblBlocks.NoVirus, TblBlocks.NoVirusDate, TblBlocks.CommentNoVirus
FROM TblBlocks;
Fritz PaulAsked:
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Rey Obrero (Capricorn1)Commented:
you can clear a date field by setting the field value to NULL
Text fields can be cleared with a zero-length string "", or with NULL

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Éric MoreauSenior .Net ConsultantCommented:
Your Update query will look like this:

UPDATE TblBlocks
SET Virus = NULL
, TestResult = NULL
, TestComment = NULL
WHERE YourConditionOnTheRowsToBeUpdated

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Rey Obrero (Capricorn1)Commented:
just use an update query, no need for codes.
Fritz PaulAuthor Commented:
Thanks it worked well.
I had to create two update queries on account of "too many fields".
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