SELECT investor_id ,  COUNT(*) FROM TRANSACTIONS GROUP BY investor_id
SELECT investor_id ,  COUNT(*) FROM TRANSACTIONS GROUP BY investor_id <table_name> : Transactions col : transaction_id | investor_id | transaction_type_code | date_of_transaction | amount_of_transaction | share_count | other_details row 1 : 1 | 6 | SALE | 1988-09-16 19:02:51 | 302507.6996 | 8718572 |  row 2 : 2 | 18 | PUR | 1982-06-06 17:19:00 | 27.257 | 9 |  row 3 : 3 | 2 | SALE | 1979-04-27 06:03:59 | 48777.969 | 8580 |  row 4 : 4 | 14 | PUR | 2001-11-28 15:06:25 | 4.5263 | 8040 |  row 5 : 5 | 8 | PUR | 1977-08-17 13:13:30 | 0.0 | 930 |  row 6 : 6 | 19 | PUR | 1985-10-08 13:13:39 | 207484122.2796 | 2751 |  row 7 : 7 | 7 | PUR | 1990-12-02 09:03:38 | 822.803 | 1522 |  row 8 : 8 | 17 | SALE | 2004-01-18 20:37:50 | 78035671.4424 | 96178 |  row 9 : 9 | 20 | PUR | 1977-08-13 02:18:47 | 82057.207 |  |  row 10 : 10 | 2 | SALE | 1981-01-28 08:07:03 | 29.3534 | 1654756 |  row 11 : 11 | 3 | SALE | 2000-04-03 20:55:43 | 0.0 | 674529892 |  row 12 : 12 | 18 | SALE | 1983-11-01 17:57:27 | 1.0 | 587 |  row 13 : 13 | 3 | SALE | 2002-04-07 20:28:37 | 183.2 |  |  row 14 : 14 | 3 | PUR | 2002-09-13 03:04:56 | 0.0 | 630021 |  row 15 : 15 | 19 | PUR | 1997-12-30 05:05:40 | 8.9 | 93191 |
col : investor_id | COUNT(*) row 1 : 2 | 2 row 2 : 3 | 3 row 3 : 6 | 1 row 4 : 7 | 1 row 5 : 8 | 1 row 6 : 14 | 1 row 7 : 17 | 1 row 8 : 18 | 2 row 9 : 19 | 2 row 10 : 20 | 1