SQL Server AVG function rounding

SQL Sever The mean value function of is used to find whether the mean value of integer type data is the result or integer , And it doesn't round . That is, rounding down . Here, first create a grade sheet , And add data as appropriate .

	CREATE TABLE sic(
	 Student number  nchar(10) not null,
	 Course no.  nchar(10) not null constraint pk_lh primary key( Student number , Course no. ),
	 achievement  int not null);
	
	INSERT INTO sic
	values  ('01','01',80),
			('01','02',90),
			('01','03',99),
			('02','02',60),
			('02','03',80),
			('03','01',80),
			('03','02',80),
			('03','03',80);	

	SELECT AVG( achievement ) AS  Divide equally  
	  FROM sic
	 GROUP BY sic. Student number  

Obviously, the student ID is 01 The average score of students should not be an integer . Here are two ways to solve .
The first is to set the data to... When creating the table float type .

	ALTER TABLE sic
	ALTER COLUMN  achievement  FLOAT NOT NULL;
	SELECT sic. Student number ,AVG( achievement ) AS  Divide equally  
	  FROM sic
	 GROUP BY sic. Student number ;
	 # You can also use DECIMAL(18,2) Format retains two decimal places 

The second way is to use SQL Server Of CAST perhaps CONVERT function .

SELECT sic. Student number ,
		AVG(
		CAST ( achievement  AS FLOAT)
		) AS  Divide equally  
	  FROM sic
	 GROUP BY sic. Student number 

SELECT CAST(AVG(CONVERT(FLOAT, achievement )) AS DECIMAL(18,2)) AS  Divide equally  
	  FROM sic
	 GROUP BY sic. Student number