OP01: Number of people who have at least one observation period that is longer than 365 days

Count number of people who have at least one observation period in the database that is longer than 365 days. 

Input:
<None>

Sample query run:
The following is a sample run of the query.
SELECT COUNT(DISTINCT person_ID) 
        AS NUM_personS 
FROM observation_period 
WHERE observation_period_END_DATE - observation_period_START_DATE >= 365
Output:
Output field list:
 Field  Description
Num_Persons Number of patients who have at least one observation period in the database that is longer than 365 days

Sample output record:
 Field  Value
Num_Persons 13482914
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