MySQL Study Notes 8: function Query

Reference Table

 

Count () is used to count the number of records

 
MySQL> Select Count(*)FromScore; MySQL> Select Count(*)FromScoreWhereStu_id=901;
 

 

Sum () summation Function

MySQL> Select Sum(Grade)FromScore; MySQL> SelectID,Sum(Grade)FromScoreWhereStu_id=901;
 

 

AVG () averaging Function

MySQL> Select AVG(Grade)FromScoreWhereC_name='Computer'; MySQL> SelectC_name,AVG(Grade)FromScoreGroup ByC_name;
 

 

Max () returns the maximum value.

MySQL> SelectC_name,Max(Grade)FromScoreWhereC_name='English'; MySQL> SelectC_name,Max(Grade)FromScoreGroup ByC_name;
 

Min () Evaluate the minimum Function

MySQL> SelectC_name,Min(Grade)FromScoreWhereC_name='Chinese'; MySQL> SelectC_name,Min(Grade)FromScoreGroup ByC_name;
 

 

Concat concatenation Function

MySQL> SelectConcat (c_name,'(', Stu_id,')')-> FromScoreOrder ByStu_id;