let bt1 = UIButton(type: UIButtonType.InfoDark)
bt1.frame = CGRectMake(130, 80, 40, 40)
let bt2 = UIButton(type: UIButtonType.RoundedRect)
bt2.frame = CGRectMake(80, 180, 150, 44)
bt2.backgroundColor = UIColor.purpleColor()
bt2.tintColor = UIColor.yellowColor()
bt2.setTitle("Tap Me", forState: UIControlState.Normal)
bt2.addTarget(self, action: "buttonTap", forControlEvents: UIControlEvents.TouchUpInside)
let bt3 = UIButton(type: UIButtonType.RoundedRect)
bt3.backgroundColor = UIColor.brownColor()
bt3.tintColor = UIColor.redColor()
bt3.setTitle("Tap Me", forState: UIControlState.Normal)
bt3.frame = CGRectMake(80, 280, 150, 44)
bt3.layer.masksToBounds = true
bt3.layer.cornerRadius = 10
bt3.layer.borderColor = UIColor.lightGrayColor().CGColor
self.view.addSubview(bt1)
self.view.addSubview(bt2)
self.view.addSubview(bt3)
}
func buttonTap(button:UIButton)
{
let alert = UIAlertController(title: "Information", message: "UIButton Event", preferredStyle: UIAlertControllerStyle.Alert)
let OKAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil)
alert.addAction(OKAction)
}
类型为nvarchar。
问题是当ContactPerson为空时没有返回ContactPerson
查询
n/a答案 0 :(得分：3)
空字符串（img{
width: 100px;
height: 100px;
}
p{
display: none;
}
div:hover + p{
display: block;
}
），与空值不同。 ''仅返回实际空值的替换值。
您可以使用ISNULL()将空字符串计算为空值：
NULLIF()答案 1 :(得分：0)