My MySQL learning Note (iii)--operator

1. Security equals operator (<=>)

SELECT NULL <=> NULLUNION ALLSELECT NULL <=> 1union ALLSELECT 1<=>0UNION allSELECT NULL = NULL

Note the difference between this operator and equals (=) is that when you determine that two values are empty, the execution results are as follows:

2. Least operator
Function: Gets the minimum value in multiple parameter values
Note: Do not mix data types using

SELECTleast(2,0),LEAST(‘a‘,‘b‘,‘c‘,‘d‘),least(10,20,NULL)

Mixed use error occurred

3. Greatest operator
Function: Gets the maximum value in multiple parameters
NOTE: null values

My MySQL learning Note (iii)--operator