对SQL_Server 部分知识的回顾

1.给SQL server 加注释，如果只有一行 “--”，如果有多行的话，请使用/*.......*/,这个跟SAS的注释一样。1.1 SQL SERVER 有行的问题，所以使用了 set nocount on set nocount off ,分别放在开始和结尾。2.能不能在查询当中生成一个新表，当然是可以的，SELECT   * INTO  new table name  SQL servercreate table tab_new as select col1,col2… from tab_old definition onlyoracleSelect * Into new_table_name from old_table_name;Mysql3.如何在查询中，行转列，列转行use testgoselect * from row_to_linedrop table row_to_line/*************** 先建一个表格，供大家好操作 use MS SQL server*********************/set nocount onCREATE TABLE row_to_line(  user_name character varying(30) NOT NULL, -- 学生名称  yingyu integer, -- 得分  yuwen integer,  huaxue integer,  wuli integer,    CONSTRAINT row_to_line_pkey PRIMARY KEY (user_name));insert into row_to_line select 'liqiu', 80, 90, 90, 89;insert into row_to_line select 'lingling', 89, 99, 100, 90;insert into row_to_line select 'xingxing', 90, 94, 97, 99;set nocount off/**************行转列 代码 SQL server*********************/set nocount onselect a.user_name,    a.title,  a.score into coltorowfrom (  (select user_name, yingyu as "score", 'yingyu' as title from row_to_line)  union (select user_name, yuwen as "score", 'yuwen' as title from row_to_line)  union (select user_name, huaxue as "score", 'huaxue' as title from row_to_line)  union (select user_name, wuli as "score", 'wuli' as title from row_to_line)) aorder by a.user_name, a.titleset nocount offdrop table coltorowselect * from coltorow/**************列转ROW代码 SQL server   method 1*********************/

SELECT 
      user_name, 
      MAX(CASE title WHEN 'yuwen' THEN Score ELSE 0 END) AS "语文",
      MAX(CASE title WHEN 'huaxue' THEN Score ELSE 0 END) AS "数学",
      MAX(CASE title WHEN 'yingyu' THEN Score ELSE 0 END) AS "英语",
      MAX(CASE title WHEN 'wuli' THEN Score ELSE 0 END) AS "生物"
FROM coltorow
GROUP BY user_name

/**************rows transfer to column code for  SQL server   method 2********************/

SELECT   a.user_name,  b.score as "语文",  c.score as "化学",  d.score as "英语",  e.score as "生物"FROM (select distinct user_name from coltorow) aleft join (select score, user_name FROM coltorow where title = 'yuwen') b on b.user_name=a.user_nameleft join (select score, user_name FROM coltorow where title = 'huaxue') c on c.user_name=a.user_nameleft join (select score, user_name FROM coltorow where title = 'yingyu') d on d.user_name=a.user_nameleft join (select score, user_name FROM coltorow where title = 'wuli') e on e.user_name=a.user_name