I have a Reporting table where i store description
tableA sno | Project |name | description | mins | 1 | prjA |nameA |ABC -10% task done| 30 | ... 3000 | prjA |nameB |ABC -70% task done| 70 |
i want to query the description field and save in another table
tableB id | valueStr | total_mins | last_sno 1 | ABC | 100 | 3000
if there is no entry in second table , i create a entry with default values
if there is and entry in second table , i update 2nd table , with the
total_mins and increment the
last_sno to that value say 3300 , so that the next time i query this table i get values from second table and based on the
Query SELCT last_sno FROM tableB where valueStr ='ABC'
the first 3 characters in the description field
SELECT max(sno), sum(mins) FROM tableA where sno > last_sno and description like 'ABC%'
Since the first table has million of rows so, i search the first table with
sno > last_sno , so that should help performance right ?
but the explain shows that it scans the same no of rows , when i query the first table from the first