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-> 1 

ISNULL()  can be used instead of =  to test whether a value is NULL . (Comparing a value to NULL  using =  always yields NULL .) 

The ISNULL()  function shares some special behaviors with the IS NULL  comparison operator. See the description of IS NULL . 

## • LEAST( value1 , value2 ,...) 

With two or more arguments, returns the smallest (minimum-valued) argument. The arguments are compared using the following rules: 

•If any argument is NULL , the result is NULL . No comparison is needed. 

•If all arguments are integer-valued, they are compared as integers. 

•If at least one argument is double precision, they are compared as double-precision values. Otherwise, if at least one argument is a DECIMAL  value, they are compared as DECIMAL  values. 

•If the arguments comprise a mix of numbers and strings, they are compared as strings. 

•If any argument is a nonbinary (character) string, the arguments are compared as nonbinary strings. 

•In all other cases, the arguments are compared as binary strings. 

The return type of LEAST()  is the aggregated type of the comparison argument types. 

## 12.4.3 Logical Operators 

mysql> SELECT LEAST(2,0); -> 0 mysql> SELECT LEAST(34.0,3.0,5.0,767.0); -> 3.0 mysql> SELECT LEAST(’B’,’A’,’C’); -> ’A’ 

<img src='content_image/662152.jpg'>

In SQL, all logical operators evaluate to TRUE , FALSE , or NULL  ( UNKNOWN ). In MySQL, these are implemented as 1 ( TRUE ), 0 ( FALSE ), and NULL . Most of this is common to different SQL database servers, although some servers may return any nonzero value for TRUE . 

MySQL evaluates any nonzero, non- NULL  value to TRUE . For example, the following statements all assess to TRUE : 

mysql> SELECT 10 IS TRUE; -> 1 mysql> SELECT -10 IS TRUE; -> 1 mysql> SELECT ’string’ IS NOT NULL; -> 1 

