MySQL's Count,max,min,sum,avg,celing,floor

Series Articles

MySQL CREATE database, create data table

MySQL's select,insert,delete,update

MySQL group By,order by

Count

Count, often used in conjunction with the group BY statement, at this point, you can understand the number of groupings after grouping. Also take the previous data sheet tb_student as an example.

1. Calculate the number of students enrolled on the same day.

Use School;  -- calculate the number of students enrolled on the same day. count (as' bydate (createdate);     

MAX

1, the largest ID

Use School;  from Tb_student; 

Min

1. Minimum ID

Use School;  from Tb_student; 

SUM

1. Find out the age of all students and

Use School;  from Tb_student; 

Avg

1. Average age of all students

Use School;  from Tb_student; 

Celing

Celing translation comes from the meaning of "ceiling", meaning, regardless of what is behind the decimal point, go upward. Like the upper age average.

Use School;  Ceiling (avg (age)) from  tb_student;   

Of course, and the ceiling corresponding to the floor function, of course, it means the opposite.

Floor

Use School;  Floor (avg.) from  tb_student;   

MySQL's Count,max,min,sum,avg,celing,floor