mssql server 排序 以及like语句 当我们按照某个字段排序时,通常使用order by语句,如果该字段存在null值,则会把null值的这条放到最上面, 那我们是否有办法解决呢? 答案是肯定的: ORDER BY CASE WHEN OrderNum IS NULL THEN 1 ELSE 0 END 这样的话,null值的这条就排队到了最后。 使用dapper查询数据时,有时...
flagascgo---将flag值等于2的放入最前面显示select*fromtestorderbycasewhenflag=2then0else1end, flagascgogotruncatetabletestdroptabletest
ORDER BY 排序列表 [ASC|DESC] 1. 2. 3. 4. 注意: ①ASC升序|DESC降序默认升序 ②ORDER BY子句可以支持单个字段,多个字段,表达式,函数,别名 ③ORDER BY子句一般是放在查询语句最后,LIMIT子句除外 1. 基本排序 查询所有员工信息,工资从高到低: SELECT * FROM employees ORDER BY salary DESC; 1. 2. 部门...
orderby(casewhen region isnullthen1else0end),region; 当region列为NULL时返回1,否则返回0。非NULL值得表达式返回值为0,因此,它们会排在NULL值(表达式返回1)的前面。如上所示的将CASE表达式作为第一个拍序列,并把region列指定为第二个拍序列。这样,非NULL值也可以正确地参与排序,是一个完整解决方案的查询。 (...
count(case when job ='MANAGER' then '1' end) 主管人数 from emp group by deptno;--如果不group,会认为所有数据是一组,返回一个数据 最后SQL优化 明知道只有一条查询结果是,请使用 LMIT 1 / TOP 1,避免全表扫描。 尽量避免使用select * ,它会全表扫描,不能有效利用索引,而且如果当该表增加了字段,...
SELECTt.column_nameAS"Field",t.data_typeAS"Type",t.data_lengthAS"Length",CASEWHENk.column_nameISNOTNULLTHEN'PRI'ELSE''ENDAS"Key",CASEWHENt.identity_column='YES'THEN'auto_increment'ELSE''ENDAS"Extra",CASEWHENt.nullable='N'THEN'NO'ELSE'YES'ENDAS"Null",t.data_defaultAS"Default",c.co...
Step1.分组:GROUP BY empid; Step2.扩展:CASE WHEN custid='A' THEN qty END; Step3.聚合:SUM(CASE WHEN custid='A' THEN qty END); 代码语言:javascript 复制 --1.1标准SQL透视转换 select empid,SUM(casewhen custid='A'then qty end)asA,SUM(casewhen custid='B'then qty end)asB,SUM(casewhen ...
For example, when a column is defined in a table as LastName and the database uses a case-sensitive collation, queries that refer to the column as Lastname or lastname will cause error 207 to return because the column name does not match. A column alias, defined in the SELECT clause,...
2019-04-01 20:37 −**一、分页查询** 方式一(row_number): ``` SELECT TOP pageSize * FROM (SELECT row_number() OVER (ORDER BY orderColumn) AS rownumber, * FROM [Table]) temptdb_row... Mouer404 0 166 MSSQL Case when用法 ...
ORDER BY TOP Because a column alias is not defined until the SELECT clause is processed, the alias name is unknown when the GROUP BY clause is processed. The MERGE statement raises this error when the <merge_matched> clause references columns in the source table but no rows are returned...