CODEWITHSUNDEEP
mysqlsqlpivot
Damon
Damon

Reputation: 21

SQL Query - Pivot loan summary by month due

This seems simple but I'm banging my head against the wall to figure it out.

I've got a single table of Loan data that I want to pivot and summarize for each month the payments were due. This is similar to a "static pool analysis" with each pool of loans for rows and the months as columns. You can see the sample data using this SQL Fiddle.

I've created a 90 second screencast to better explain the pivot and summary results I need if that helps. Thanks for your help!

Upvotes: 1

Views: 384

Answers (1)

vanlee1987
vanlee1987

Reputation: 181

If it doesn't need to be dynamic, using a CASE WHEN or IF statement within the SUM should function as a PIVOT in MySQL:

SELECT 
  PoolMonth, 
  SUM(OriginationAmt) AS Origination,
  SUM(IF(PmtDue = 201512, AmtPaid, 0)) AS `201512`,
  SUM(IF(PmtDue BETWEEN 201512 AND 201601, AmtPaid, 0)) AS `201601`,
  SUM(IF(PmtDue BETWEEN 201512 AND 201602, AmtPaid, 0)) AS `201602`
FROM
  Loans
GROUP BY
  PoolMonth;

http://sqlfiddle.com/#!9/47701/16

This is a bit verbose to get the total OriginationAmt, the running total by PoolMonth/PmtDue, and only output the latest running totals, without hardcoding anything, but here we go :-)

SELECT
  t.PoolMonth,
  t.TtlOriginationAmt,
  t.PmtDue,
  t.RtAmtPaid
FROM
  (
    SELECT 
      l.PoolMonth,
      l.OriginationAmt,
      orig.TtlOriginationAmt,
      l.PmtDue,
      /* Row_Number() equivalent for MySQL http://blog.sqlauthority.com/2014/03/09/mysql-reset-row-number-for-each-group-partition-by-row-number/ */
      /* Assign a Row Number for each Payment Due month for the individual Pool month in ascending order (ORDER BY clause important in this subquery) */
      @RowNumber := CASE WHEN @PoolMonth = l.PoolMonth AND @PmtDue = l.PmtDue THEN @RowNumber + 1 ELSE 1 END AS PoolPmtRowNumber,
      /* Use the total count of PmtDue month rows for each PoolMonth so we can limit our results to the final row */
      lr.PoolPmtLastRow,
      l.AmtPaid,
      /* Running total of Amount Paid for the individual Pool month in order of Payment Due month (ORDER BY clause important in this subquery) */
      @RtAmtPaid := CASE WHEN @PoolMonth = l.PoolMonth THEN @RtAmtPaid + l.AmtPaid ELSE l.AmtPaid END AS RtAmtPaid,
      /* Keep track of the Pool month we're totalling */
      @PoolMonth := l.PoolMonth,
      /* Keep track of the Payment Due month we're ordering */
      @PmtDue := l.PmtDue
    FROM
      Loans l
    JOIN
      /* Get the Total Origination Amount */
      (SELECT PoolMonth, SUM(OriginationAmt) AS TtlOriginationAmt FROM Loans GROUP BY PoolMonth) orig ON orig.PoolMonth = l.PoolMonth
    JOIN
      /* Get the total number of records by Pool/Payment due month so we can filter to the last row */
      (SELECT PoolMonth, PmtDue, COUNT(1) AS PoolPmtLastRow FROM Loans GROUP BY PoolMonth, PmtDue) AS lr ON lr.PoolMonth = l.PoolMonth AND lr.PmtDue = l.PmtDue
    CROSS JOIN
      /* Reset the variables we need for tracking */
      (SELECT @RtAmtPaid:=0,@PoolMonth:=0,@PmtDue:=0,@RowNumber:=0) var
    /* Order by Pool/Payment Due month */
    ORDER BY
      l.PoolMonth,
      l.PmtDue
  )t
WHERE
  /* Filter to the last row */
  t.PoolPmtRowNumber = t.PoolPmtLastRow;

http://sqlfiddle.com/#!9/47701/45

From there, it should be really easy to pivot your results in Excel or anywhere else.

Upvotes: 2

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