How to Calculate Date Differences Between Consecutive Records in an Access Database Using SQL?

Calculating Date Differences Between Sequential Records in Access Databases using SQL

Analyzing temporal data often involves determining the time elapsed between successive entries. This article demonstrates how to calculate date differences between consecutive records sharing the same account number within an Access database using SQL.

Method 1:

The following SQL query calculates the date difference for consecutive records associated with account number 1001:

SELECT  T1.ID, 
        T1.AccountNumber, 
        T1.Date, 
        MIN(T2.Date) AS NextDate, 
        DATEDIFF("D", T1.Date, MIN(T2.Date)) AS DaysDifference
FROM    YourTable AS T1
LEFT JOIN YourTable AS T2
    ON T1.AccountNumber = T2.AccountNumber
    AND T2.Date > T1.Date
GROUP BY T1.ID, T1.AccountNumber, T1.Date;

This approach utilizes a LEFT JOIN to identify the subsequent date for each record and then employs the DATEDIFF function to compute the difference in days.

Method 2:

Alternatively, this query achieves the same result:

SELECT  ID,
        AccountNumber,
        Date,
        NextDate,
        DATEDIFF("D", Date, NextDate) AS DaysDifference
FROM    (   SELECT  ID, 
                    AccountNumber,
                    Date,
                    (   SELECT  MIN(Date) 
                        FROM    YourTable AS T2
                        WHERE   T2.AccountNumber = T1.AccountNumber
                        AND     T2.Date > T1.Date
                    ) AS NextDate
            FROM    YourTable AS T1
        ) AS T;

This method uses a subquery to find the next date for each record before calculating the date difference.

Example Output (Account Number 1001):

Both queries produce a similar result set:

AccountNumber	Date	DaysDifference
1001	10/9/2011	2
1001	12/9/2011	8
1001	20/9/2011	NULL

The NULL value indicates that there is no subsequent record for the last entry. Remember to replace "YourTable" with the actual name of your table.

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