herolinfeng的专栏

SELECT * FROM table_name ORDER BY rand() LIMIT 5;rand在手册里是这么说的:RAND() RAND(N) 返回在范围0到1.0内的随机浮点值。如果一个整数参数N被指定，它被用作种子值。 mysql> select RAND();-> 0.5925mysql> select RAND(20);-> 0.1811mysql> select RA

labels标号：create procedure p17()label_1: begin   label_2: while 0 = 1 do      leave label_2;   end while;   label_3: repeat       leave label_3;      unitil 0 = 0   end repeat;   label_4: loop