How to update MySQL table with a cumulative count of events with the same date
- by John
I have a table which I pull data from. This data has a date and a stock symbol. There can be multiple rows of data with the same date and different stock symbols. I need to update the table so that there is a running total for all rows with the same date. When a new date occurs the cumulative count re-sets to 1 and then resumes.
A typical query:
mysql> SELECT Sym 'sym' , fdate as 'FilledDate', TsTradeNum 'numT'
-> FROM trades_entered_b2
-> WHERE fDate >= '2009-08-03' AND fDate <= '2009-08-07'
-> LIMIT 10;
+------+------------+------+
| sym | FilledDate | numT |
+------+------------+------+
| WAT | 2009-08-03 | 0 |
| ALGN | 2009-08-04 | 0 |
| POT | 2009-08-05 | 0 |
| PTR | 2009-08-06 | 0 |
| SCHW | 2009-08-06 | 0 |
| FDO | 2009-08-07 | 0 |
| NBL | 2009-08-07 | 0 |
| RRC | 2009-08-07 | 0 |
| WAT | 2009-08-08 | 0 |
| COCO | 2009-08-08 | 0 |
+------+------------+------+
What I want:
+------+------------+------+
| sym | FilledDate | numT |
+------+------------+------+
| WAT | 2009-08-03 | 1 |
| ALGN | 2009-08-04 | 1 |
| POT | 2009-08-05 | 1 |
| PTR | 2009-08-06 | 1 |
| SCHW | 2009-08-06 | 2 |
| FDO | 2009-08-07 | 3 |
| NBL | 2009-08-07 | 4 |
| RRC | 2009-08-07 | 5 |
| WAT | 2009-08-08 | 1 |
| COCO | 2009-08-08 | 2 |
+------+------------+------+
What I need to do is update the TsTradeNum column with the correct values. I have tried to create a function and various queries all failed.
Any ideas? Thanks in advance