一、关于数据库
1.中的NULL值
数据库中只有三种类型:true false和unknown
UNLL类型就是UNKNOWN 是不知道这个值是什么,所以不能在WHERE条件中=NULL(等于) 或<>(不等于)比较
可以:WHERE 某列 IS NULL --PS:null在管理器中NULL(大写)插入才行,不然插进去的是字符串。
2.UNION ALL 举例:用于底部汇总:
SELECT 销售员,销售金额=SUM(销售数量*销售价格) FROM MyOrders GROUP BY 销售员
UNION ALL
SELECT '总销售额:',SUM(销售价格*销售数量) FROM MyOrders
二、查询是否包含某一字符串
LIKE 和 CHARINDEX查询是否包含某一值
据说CHARINDEX效率高一点,具体:
SELECT LINE_ID,LINE_CODE,LINE_TITLE,LINE_DESTINATION,LINE_DAYS,LINE_PRICE_NORMAL FROM T_PRODUCT_LINE_INFO WHERE LINE_DAYS BETWEEN 1 AND 6 AND ','+LINE_DESTINATION+',' LIKE '%,KRA,%' --LIKE SELECT LINE_ID,LINE_CODE,LINE_TITLE,LINE_DESTINATION,LINE_DAYS,LINE_PRICE_NORMAL FROM T_PRODUCT_LINE_INFO WHERE LINE_DAYS BETWEEN 1 AND 6 AND CHARINDEX(',KRA,',','+LINE_DESTINATION+',')>0 --CHARINDEX
cookie:
HttpCookie MyCookie = new HttpCookie("name"); MyCookie.Value = "jd"; MyCookie.Expires = DateTime.Now.AddMonths(3); MyCookie.Domain = "www.51yougo.com"; string str = Request.Cookies["name"].Value;
正则 表达式求字符串中一个字符个数总和:
string a = Regex.Matches(b, "a").Count.ToString();
方法二:
public static int indexOf (字符串/字符,int从第几位开始,int共查几位)
string tests = "1absjjkcbfka2rsbcfak2bfka1"; //测试字符串
int i = tests.IndexOf("2b",5,tests.Length-5); //查找从第五字符向后查找“2b”
textBox2.Text = i.ToString();
int i = tests.IndexOf("2b",5,2); //查找从第五字符向后查找两个字符是否有“2b”
返回-1 表示未找到“2b”
二、window.location.search方法总结。
使用方法
var url=window.location.search; var Request = new Object(); if(url.indexOf("?")!=-1){ var str = url.substr(1); strs = str.split("&"); for(var i=0;i<strs.length;i++){ Request[strs[i].split("=")[0]]=strs[i].split("=")[1]; } } //xxx.htm?a=1 if(Request['a']!=undefined){ alert(Request['a']); }