Question

i have one problem while making a query

wellid       dated              drillid
1        2000-05-01 11:30:00      123  
1        2000-05-01 11:30:00      124  
1        2000-05-01 11:35:00      123  
1        2000-05-01 11:36:00      124           

now i want to make a query that return one row when drillid is equal to 123, but there are two dated for drillid 123, so i want only those dated row whose datetime is maximum as compared to other whose drillid is 123 or 124.

suppose i run query for drillid 123 then it must return me

wellid       dated              drillid
1        2000-05-01 11:35:00      123  

but not return me

wellid       dated              drillid
1        2000-05-01 11:30:00      123  

Answer 1

SELECT wellid, MAX(dated), drillid
FROM (table name)
WHERE drillid = 123
GROUP BY drillid