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ernest.morariu
Starting Member
2 Posts |
 Posted - 2012-09-19 : 06:24:54
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| Hi !Suppose we have a table T with the following structure:Id int primary keyA int Let's also suppose the table T contais the following record :Id A1 5I would like to know if the following sql is executed atomically:Update T set T.A = T.A + 1 where T.Id = 1 and T.A < 10Does this sql dipends on the current transaction isolation level ? Supose there is another client that may execute concurrently the following sql command:Update T set T.A = 50 where T.Id =1 Put it differently, is there any risk I can find in the field A the value of 51 ?(which would be undesirable for me)Thank you !Ernest |
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TG
Master Smack Fu Yak Hacker
6065 Posts |
Posted - 2012-09-19 : 10:30:51
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| you will not end up with A=51 with any isolation level. READ UNCOMMITTED does not apply to update statements and any other isolation level will not allow this to be violated (and T.A < 10).Be One with the OptimizerTG |
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ernest.morariu
Starting Member
2 Posts |
Posted - 2012-09-20 : 08:21:14
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| Thank you TG!Ernest |
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sql update atomicity