Mysql - Query to get 5 rows from each category, Select first least max row per group in sql
Query to get 5 rows from each categoryConsider that you have a table as below and you want to select some five rows from each column. In such situation you can use join statement.
ID Dept Names --------------------- 1 ECE Mark 2 ECE Kris 3 ECE Chris 4 EEE Ben 5 EEE Chris 6 CSE Marc 7 CSE Math 8 CSE Sara
SELECT t1.id,t1.Names,t1.Dept,COUNT(t2.id) AS cnt FROM COLLEGE AS t1 LEFT JOIN COLLEGE AS t2 ON (t1.Names, t1.id) <= (t2.Names, t2.id) AND t1.Dept = t2.Dept GROUP BY t1.id,t1.Names,t1.Dept HAVING cnt <= 4 ORDER BY t1.Dept, cnt
ECE EEE CSE ------- ------ -------- Mark Ben Marc Kris Chris Math Chris Sara
You can modify this query and can get first or last five rows from your database. This query takes little time to execute than other queries, but it will reduce the execution of multiple quries. I feel that it is better in performance insted of executing multiple queries.
The topic on Mysql - Query to get 5 rows from each category is posted by - Math
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