Problem description

sql:

 SELECT ID ,COUNT(ID) as favoriteCount,productID  FROM l_favorite GROUP BY productID

Report errors ：
MySql.Data.MySqlClient.MySqlException:“Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column ‘lec.l_favorite.ID’ which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by”

Cause analysis ：

It felt strange at first , Run in the database management tool without error ,EF You'll report a mistake again . And there are times mistakes , Sometimes they don't report .
First, I directly searched the error content , Then a bunch of articles are written directly , Get rid of mysql In the configuration file sql_mode=ONLY_FULL_GROUP_BY To configure .
It's very speechless , Don't say the reason for the error , It doesn't solve the problem , Directly solve the configuration items that generate errors , Since the default configuration is like this , That must make sense , Don't change the configuration easily , It's not a good habit .
Then translated this paragraph in English , Probably means to say ID This field has no aggregation .
Well, … Looked at the sql, I'm careless , many select There's a ID Field , And the grouping field is productID . Cause the database to think , Put several different ID Aggregate into one ID, It's illegal .

Solution ：

hold select There is no aggregation behind ID Just remove the field .