Re: Different data types

[Rick James]

"how does someone create a query that pulls rock weights from 15 to 30 lbs if the data is stored as varchar?"

What are you asking?
1. "How do I store weights that might be in lbs or kg?"
2. "How do I store approximate values, like '15-30 lbs'?"
3. "Given some records with specific values, how do I fetch all values in some range"?

Answers:
1. Convert every thing to standard metric values.
2. That gets complex.
3. WHERE weight BETWEEN 15 and 30 (except that #1 says these need to be converted to kg)

And to repeat Peter's plea: Do not use EAV design!

The compromise for EAV: In the table, store explicitly the columns that you might search on (eg, `weight`). Then have a blob for the rest of the junk. I like JSON for the blob. Your application code would parse the blob to display the other fields.