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NOLOCK and Inserts

William Assaf shows us the bad idea of the day:

Error 1065 states “The NOLOCK and READUNCOMMITTED lock hints are not allowed for target tables of INSERT, UPDATE, DELETE or MERGE statements.”  However, NOLOCK can still dangerously be used as the source of the write. (NOLOCK can also fail with error 601 on even basic SELECT statements, but coders just aren’t always scared off by that.)

Here’s a very elementary example to share at parties in order to scare developers away from using NOLOCKs adventurously:

Read on for an example which shows the level of pain you can find yourself in with NOLOCK.