greatest() function in mysql returns blob -
i trying use greatest function of mysql
if trying add 1 column sub queries returning me blob
value , tried using mysql workbench
, tried phpmyadmin
results same.
below sql query :
select greatest(pm10index,pm2index,noindex,so2index,o3index,nh3index,coindex) table ;
here values fetched sub queries.
the issue occurs when add pm10index
column in function , if particular column pm10index
removed function returns highest value correctly .
below value pm10index
pm10, (case when pm10 = 0 0 when pm10 <=50 pm10 when pm10 >50 , pm10 <=100 pm10 when pm10 >100 , pm10 <=250 100+(pm10-100)*0.666 when pm10 >250 , pm10 <=350 200+(pm10-250) when pm10 >350 , pm10 <=430 300+(pm10-350)*1.25 when pm10 >430 400+(pm10-430)*1.25 end) pm10index
pm10
defined varchar
datatype , while other fields defined varchar
it great if can me here . in advance .
below value pm10index ... pm10 defined varchar datatype
there no varchar (or type of string) in code provided. if did cast data varchar, going end odd results (try select greatest('2','100');
).
while mysql best compare strings , numbers, sooner or later going break. unless have @ least consistent data types (and should correct data types) code cannot relied upon.
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