Search a range of cases/records

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Greetings:

I have a dataset of two columns:
price amount
99.5   10000
99.7   8000
100    3000
100.1  1000
100.5  500
100.8  1500
105    2000
200    100
etc
I have to write a SQL query on how many price tags are within [price+-1]
such as 98.5 to 100.5, 100+-1,etc for each records.
Here I know the price tags counts are 5 for 99.5-100.5, 5 for
99.7-100.7, 6 for 99-101, etc
How should I do for all of the records?

Thanks in advance.

Wei
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