This is probably very easy question for you sql gurus, but I never used sql before.
If the table "Person" has 3 rows : Name (primary key), Age and City, I know I can get all rows like this :
开发者_JAVA技巧SELECT * FROM Person;
But if the table looks like this :
Name Age City
-------------------
A 2 NY
B 4 BE
C 6 PA
What sql command do I have to use to get (for example) the 2nd row? I know the Name is B.
SELECT * FROM Person WHERE Name = 'B';
This solves this particular problem, but you can visit w3schools sql tutorial for the starting.
SELECT * FROM Person
WHERE Name = 'B';
Try SELECT * FROM Person WHERE Name='B'
more about select syntax you can find here http://dev.mysql.com/doc/refman/5.0/en/select.html
You should avoid using primary keys that are related to any data in the entity. There is almost never a good pick. Primary keys should not change... Names can change (Both for cities and Persons) Also a SSN might "look" like a good candidate, but even they rotate over time, and you might happen to employ an illigal alien with a faked SSN Number ;)
So please allways use an integer that just counts up, or a guid.
Besides that, the answer has been posted several times already...
Rather than ask a question about each aspect of sql on here (you'll probably have quite a few), do a bit of reading first:
http://w3schools.com/sql
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