https://dev.mysql.com/doc/refman/5.7/en/non-typed-operators.html

1概述

a 操作符 =，用于赋值（assignment）还是比较(comparison),优先级不同

b 如果同级别优先级，赋值时从右往左，其他情况从左往右

--优先级从上到下依次递减  
INTERVAL  
BINARY, COLLATE  
!  
- (unary minus), ~ (unary bit inversion)  
^  
*, /, DIV, %, MOD  
-, +  
<<, >>  
&  
|  
= (comparison), <=>, >=, >, <=, <, <>, !=, IS, LIKE, REGEXP, IN  
BETWEEN, CASE, WHEN, THEN, ELSE  
NOT  
AND, &&  
XOR  
OR, ||  
= (assignment), :=  

   

2 比较运算符

a 比较类运算符，结果有1(TRUE)，0(FALSE)，NULL，除了LEAST() 和 GREATEST()

b 会根据实际值，数值和字符串会自动转换

c 比较符 =,>,<,>=,<=,<>,!= 不仅能用于值比较，还可以用于row comparisons

d 默认情况下，字符串比较大小写不敏感