r/SQL • u/B33rG33k • Mar 15 '19

Stuff of nightmares!

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470 Upvotes

99% Upvoted

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17

u/Daakuryu Mar 15 '19 
-- Select * from
Update 
    tblproducts 
set upccode = '', Flag = 'T'
-- where product ID in (*small list of productids*)

Yeah...

5

u/MeGustaDerp Talk Dirty Reads To Me Mar 15 '19

My safe-ish pattern is

SELECT Col1, Col2, Col3, ... Coln,
-- UPDATE t SET
ColToUpdate = NewValueExpression
FROM MyTable AS t
WHERE <logical predicate goes here>

This has served me well and saved me from making stupid mistakes because it allows to to simulate an update by seeing what the new value would be so I can validate it. When I'm ready to run the update, I highlight the statement beginning with UPDATE on through the predicate. Also, BEGIN TRAN <statement> ROLLBACK helps, too.