use yuyongTest
--exists:如果查询语句返回至少一行数据则返回true,否则返回false
if exists(select * from student where number=(-1))
print(‘Y‘);
else
print(‘N‘);
if exists(select * from student where number>=(-1))
print(‘Y‘);
else
print(‘N‘);
原文：http://blog.csdn.net/yongyu_it/article/details/44646783