运算符优先级顺序
最高优先级 :=
1 ||, or, xor
2 &&, and
3 between, case, when, then, else
4 =, <=>, >=, >, <=, <, <>, !=, is, like, regexp, in
5 |
6 &
7 <<, >>
8 -, +
9 *, /, div, %, mod
10 ^
11 - (unary minus), ~ (unary bit inversion)
12 !, not
最低优先级 binary, collate
原文：http://www.cnblogs.com/yuyue2014/p/4451035.html