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Transaction isolation level

Transaction isolation level:1. Uncommitted Read (NoLock)2. Committed Read (blocking)3. Repeatable Read (phantom)4. Snapshot  (no blocking)5. Serializable (no blocking)Dirty Read:(DR)Non Repeatable Read:(NRR)Phantom:(P)Great...

2009-05-19

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Question of the Day

ORDER BY alias

There is a table tmp_tab: 

CREATE TABLE tmp_tab (
id int,
val int
);
INSERT INTO tmp_tab VALUES
(1, 1),
(2, NULL),
(3, 3),
(4, 4),
(5, 5);
You want to order the rows ids by the following expression: 
    ISNULL(val, id) + 1
Which of the following queries produces the expected ordering and why? (Select all correct)

See possible answers