SQLdistinct用法---count(distinct字段1,字段2) 1.作用于单列:select distinct 字段1 from t; 2.作用于多列: 只有两行记录行完全相同才可去重 3.COUNT统计:可用再count里对字段去重计算select *,count(distinct 字段1) as alias from t; count(distinct 字段1,字段2) 对字段1和字段2联合去重计数 4.distinc...
与 都是一样,DISTINCT 和 GROUP BY 后边的几个字段,都会组合起来成为一个整体,用来识别唯一值/分组。就像组合索引。 没有谁先谁后的,分开出来的情况。 其中DISTINCT 字段1,字段2... 与 EXCEL中 利用 字段1,字段2 组合去重的效果一样。
一、三次握手 (1)TCP报文格式 (2)比较重要的字段 (3)TCP的三次握手详解 第一次握手: 首先客户端向服务器端发送一段TCP报文,其中: 标记位为SYN,表示“请求建立新连接”; 序号为Seq=X(X一般为1); 随后客户端进入SYN-SENT阶段。 第二次握手: 服务器端接收到来自客户端的TCP报文之后,结束LISTEN阶段。并返回...
试试这个
1. distinct-distinction n.差别;区分;卓著2. major-majority n.大多数;大半3. elect-election n.选择;;选举某人4. race-racial adj.人种的;种族的5. apply-applicant n.申请人6. indicate–indication n.指出;指示;暗示7. punish-punishment n.处罚;惩罚8. correct-correction n.改正;纠正;修正9. objec...
In contrast to MASP-1 and MASP-2, the proteinase activity of MASP-3 has not been described previously. We show here the proteolytic activity of the ... CL Cortesio,W Jiang - 《Archives of Biochemistry & Biophysics》 被引量: 98发表: 2006年 Distinct Longitudinal Associations of MBL, MASP-...
TIE-1 and Tie-2 define a new class of receptor tyrosine kinases that are specifically expressed in developing vascular endothelial cells. To study the functions of Tie-1 and Tie-2 during vascular endothelial cell growth and differentiation in vivo , targeted mutations of the genes in mice were...
Distinct functions of COX-1 and COX-2 The enzymes that convert arachidonic acid to prostaglandin H2 are named cyclooxygenase-1 (COX-1) and COX-2. The properties of COX-1 are different from thos... I Morita - 《Prostaglandins & Other Lipid Mediators》 被引量: 520发表: 2002年 Distinct mec...
Here, we identified that the protein deacetylase sirtuin 2 (SIRT2) as a novel interactor of LMAN2. Loss of SIRT2 expression resulted in exosomal release of LMAN2, a Golgi resident protein, along with increased exosomal release of GPRC5B. Furthermore, knockout of SIRT2 increased total number...
sql(2) DISTINCT SELECT DISTNCT 列名称 FROM 表名称 SQL SELECT DISTINCT 语句 在表中,可能会包含重复值。 关键词 DISTINCT 用于返回唯一不同的值。 语法: 新建数据库 test 新建表 Table_1 新建列 Mike 广州 mary 深圳 Mike 南京 huali 北京 查询:...