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Equivalent LEFT JOIN SQL?

Posted on 2011-02-21
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Last Modified: 2012-05-11
A while back I asked a question which helped me to build the following (first) SQL statement. Out of interest. Could somebody tell me if both of the following statements are identical. Is the alias just for convenience, or could it alter the output in any way?

SELECT t1.* FROM user_group_link AS t2 LEFT JOIN user AS t1 ON t2.user_id = t1.id WHERE t2.group_id=[b]INPUT[/b]

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SELECT user.* FROM user_group_link LEFT JOIN user ON user_group_link.user_id = user.id WHERE user_group_link.group_id=[b]INPUT[/b]

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Question by:numberkruncher
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markterry earned 500 total points
ID: 34944612
Yes, they are the same. Aliases are simply to shorten your object names in a query. This way you can give your tables descriptive names, and not have to be constantly inconvienced by the name while typing.
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by:markterry
ID: 34944635
in fact, if the colum names are unique to all tables, you do not even need the tablename.columnname, you can just put colum name. But this is not good practice.
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by:numberkruncher
ID: 34944704
Thanks, I wasn't sure what the AS was giving an alias to the table name or whether it was giving a name to a set of results which had to be re-addressed.
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