2.比较运算符 等于 mysql> select 1=0,1=1,null=null; 不等于 mysql> select 1<>0,1<>1,null<>null; 安全等于 mysql> select 1<=>1,2<=>0,0<=>0,null<=>null; 小于 mysql> select 'a'<'b','a'<'a','a'<'c',1<2; 小于等于 mysql> select 'bdf'<='b','b'<='b',0<1; 大于 mysql> select 'a'>'b','abc'>'a',1>0; 大于等于 mysql> select 'a'>='b','abc'>='a',1>=0,1>=1; BETWEEN mysql> select 10 between 10 and 20, 9 between 10 and 20; IN mysql> select 1 in (1,2,3), 't' in ('t','a','b','l','e'), 0 in (1,2); IS NULL mysql> select 0 is null,null is null; IS NOT NULL mysql> select 0 is not null, null is not null; LIKE mysql> select 123456 like '123%', 123456 like '%123%', 123456 like '%321%'; REGEXP mysql> select 'abcdef' regexp 'ab', 'abcdefg' regexp 'k';
3.逻辑运算符 非 mysql> select not 0, not 1, not null; mysql> select ! 0, ! 1, ! null; 与 mysql> select (1 and 1), (0 and 1), (3 and 1), (1 and null); mysql> select (1 && 1), (0 && 1), (3 && 1), (1 && null); 或 mysql> select (1 or 0), (0 or 0), (1 or null), (1 or 1), (null or null); mysql> select (1 || 0), (0 || 0), (1 || null), (1 || 1), (null || null); 异或 mysql> select (1 xor 1), (0 xor 0), (1 xor 0), (0 xor 1), (null xor 1); mysql> select (1 ^ 1), (0 ^ 0), (1 ^ 0), (0 ^ 1), (null ^ 1);