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Join Date: Mar 2004
Posts: 732
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Master Poster
Is there a way I could create a variable that belongs to a table much like a static variable belongs to a class? So it "thing=1, person=2" were variables belonging to the table structure (not each row), then I could do something like this:
SELECT *
FROM table
WHERE type = table.thing OR type = table.person
I haven't touched sql in months, and I have a feeling this is something very simple.
SELECT *
FROM table
WHERE type = table.thing OR type = table.person
I haven't touched sql in months, and I have a feeling this is something very simple.
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Join Date: Jun 2005
Location: Kansas City, Missouri, USA
Posts: 344
Reputation:
Rep Power: 4
Solved Threads: 4
Posting Whiz
I think I understand the functionality you are looking for. If not, I apologize now.
I've never seen anything like you described. This functionality is usually accomplished using what are commonly referred to as "Lookup Tables". A Lookup Table is usually a relatively small table with usually just 2 columns: an ID and a Name string. For example:
This table may contain data such as:
Then your "car" table may look like this:
See? Your car table uses the manufacturer_id instead of spelling out the manufacturer for every row. This is because, eventually your car table may have hundreds of thousands of rows, so why waste space inserting the manufacturer names in every row when there are only a handful of manufacturers.
So when you query, you do something like this:
This help?
I've never seen anything like you described. This functionality is usually accomplished using what are commonly referred to as "Lookup Tables". A Lookup Table is usually a relatively small table with usually just 2 columns: an ID and a Name string. For example:
Manufacturer =================== manufacturer_id BIGINT manufacturer_name VARCHAR(50)
This table may contain data such as:
manufacturer_id manufacturer ========================= 1 Acura 2 Chevy 3 Ford 4 Honda 5 Toyota
car_id manufacturer_id model_id year mileage color ================================================ 1 3 2 2004 24350 green 2 3 9 2002 56771 black 3 1 34 1999 78200 silver
See? Your car table uses the manufacturer_id instead of spelling out the manufacturer for every row. This is because, eventually your car table may have hundreds of thousands of rows, so why waste space inserting the manufacturer names in every row when there are only a handful of manufacturers.
So when you query, you do something like this:
SELECT manf.manufacturer_name ,mod.model_name ,c.year ,c.mileage ,c.color FROM car c INNER JOIN manufacturer manf ON c.manufacturer_id = manf.manufacturer_id INNER JOIN model mod ON c.model_id = mod.model_name WHERE mileage < 50000 ORDER BY year DESC
This help?
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