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sth_Weird
Starting Member
38 Posts |
 Posted - 2014-09-15 : 04:31:33
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| hi,I am looking for the best way to select rows from a table, using primary keys.This is what I have:Table "A" has about 1000 entries, one column contains a foreign key (unique) that points to an entry in another table "B". Table "B" has a lot of rows, let's say 100000+, up to 500000. I want to select all rows from table "B" that are refered to in table "A". Now, the number of entries in table "B" is a lot larger than the 1000 entries in table "A". Does that matter when it comes to picking the best sql query to select the rows? Should I use a table join, or use SELECT * FROM B WHERE PrimaryKey in (SELECT ForeignKey FROM A)? Or maybe even use WHERE EXISTS (...)? By the way I only need the columns of table "B" in my result.thxsth_Weird |
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gbritton
Master Smack Fu Yak Hacker
2780 Posts |
Posted - 2014-09-15 : 08:07:33
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| Just join and select the resulting columns that come from b |
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SwePeso
Patron Saint of Lost Yaks
30421 Posts |
Posted - 2014-09-15 : 08:35:20
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Do you have a referential constraint? If so, use join.If not, consider EXISTS.
Microsoft SQL Server MVP, MCT, MCSE, MCSA, MCP, MCITP, MCTS, MCDBA |
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Lokanatha
Starting Member
1 Post |
Posted - 2014-09-17 : 21:53:49
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| Better use Joins for more details on [url]<a href="http://skillgun.com/sql/interview-questions-and-answers">SQL Questions</a>[/url] in http://skillgun.com |
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sth_Weird
Starting Member
38 Posts |
Posted - 2014-09-26 : 05:57:12
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| thank you! |
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Fastest way to select rows using the primary keys