代码如下 select distinct G.* ,(select BUSINESS_NAME from BusinessInfo where BusinessInfo.BUSINESS_BID=G.G_BUSINESS_ID) as BUSINESS_NAME ,(select sum(StockGNum) from StockDetail where StockDetail.StockGID =G.G_ID) as StockGNum ,(select sum(StockRemovalGNu
JavaScript判断非空的语句一般为: var elvis; if (typeof elvis !== "undefined" && elvis !== null) { alert("Elvis isn't a null object!"); } 当然,如果你使用CoffeeScript的话,写法就更简单了: alert "Elvis isn't a null object!" if elvis? 版权声明:本文为博主原创文章
mysql中时间字段datetime怎么判断为空和不为空一般为空都用null表示,所以一句sql语句就可以.select * from 表名 where 日期字段 is null;这里要注意null的用法,不可以用=null这样的形式表示.相反,要取出不为空的数据,就是is trueselect * from 表名 where 日期字段 is true;
1.字符串参与判断时:非空即为真判断字符串为空的方法if(str!=null && str!=undefined && str !='')可简写为if(!str){ console.log(str)}2.数字参与if判断:非0非NAN即为真 var i = 0;if(i){ alert('here');}else{ alert('test is ok!');} 输出结果为here var i = 0;if(i){ alert('here');}else{ alert(