MySQL Find delete duplicate data and keep only one instance detailed _php instance

There is such a table, the table data and the results are as follows:

school_id	School_name	Total_student	Test_takers
1239	Abraham Lincoln High School	55	50
1240	Abraham Lincoln High School	70	35
1241	Acalanes High School	120	89
1242	Academy of the Canyons	30	30
1243	Agoura High School	89	40
1244	Agoura High School	100	50

We can see that School_name's field values have duplicate data (Abraham Lincoln High School and Agoura High School appear two), so how do you delete the two data so that only the two values appear once? The implementation methods are as follows:

1, delete duplicate records, save the least ID of the one

Delete from ' test ' WHERE ' school_name ' (SELECT ' school_name ', '
test ' 
GROUP by ' School_name ' has 
cou NT (*) >1) and school_id not in (select min (school_id) from test group by SCHOOL_ID have Count (*) >1)

Use the group by has syntax to query for duplicate data, and then delete the duplicate data and keep the school_id of the smallest one.

2, delete the duplicate record, save the largest one of the ID

Delete from ' test ' WHERE ' school_name ' (SELECT ' school_name ', '
test ' 
GROUP by ' School_name ' has 
cou NT (*) >1) and school_id not in (select Max (school_id) from test group by SCHOOL_ID have Count (*) >1)

The principle is the same as above.

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