MySQL winter vacation self-study 2022 12 (2)

--  The absolute value 
select abs(-10);#10
select abs(10);#10
select abs(-1.1);#1.1

-- ceil  Rounding up 
select ceil(1.1);#2
select ceil(-1.1);#-1

-- floor  Rounding down 
select floor(1.1);#1
select floor(-1.1);#-2

--  Take the maximum value of the list 
select greatest(1,2,3);
select greatest(1.1,2,3);

--  Take the minimum value of the list 
select least(1,2,3);
select least(-1,2,3.0);

--  modulus 
select mod(5,2);#1
select mod(-5,2);#-1
select mod(5,-2);#1
select mod(-5,-2);#-1

--  PI 
select PI();

--  return x Of y Power 
select pow(2,3);# 8
select pow(2.0,3.0);# 8
select pow (2,-1);#0.5

-- 0-1 The random number 
select rand();

--  Return integer , rounding 
select round(4.5);#5
select round(4.4);#4
select round(-4.5);#-5
select round(-4.4);#-4

select round(3.5415,3);# Keep three decimal places ,3.542

--  Cut the decimal directly to the specified number of digits 
select truncate(3.1415,3);#3.141  No rounding