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Databases

Posted by Ikuyasu Usui
Ikuyasu Usui
36 Points

For INNER JOIN, do you always get the same query result if you switch the two tables in the query?

I figured that two query statements produce the same results:

SELECT mk.MakeName, md.ModelName FROM make AS mk INNER JOIN model AS md ON mk.MakeID = md.MakeID;

SELECT mk.MakeName, md.ModelName FROM model AS md INNER JOIN make AS mk ON mk.MakeID = md.MakeID;

Is it always the case for INNER JOIN? Is there any rule or a common practice on which table you should start querying when you use INNER JOIN?

1 Answer

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

You're right, it makes no difference in which order the tables are used. An INNER JOIN is a symmetric operation.

I don't know if there's any official convention, but I would generally start with the table that the first item in the SELECT comes from. So in this case, I would use your first example.