+CAST((SELECT col2FROM tbWHERE col1=a.col1AND col2NOT IN(MAX(a.col2),MIN(a.col2)))as varchar) ELSE '' END +CASE WHEN COUNT(*)>=2 THEN ','+CAST(MAX(col2)as varchar) ELSE '' END FROM tb a GROUP ...
- **COUNT**：计算行数，`SELECT COUNT(*) AS totalcount FROM table1`。 - **SUM**：求和，`SELECT SUM(field1) AS sumvalue FROM table1`。 - **AVG**：计算平均值，`SELECT AVG(field1) AS avgvalue FROM ...
- 总数：`SELECT COUNT(*) AS totalcount FROM table1` - 求和：`SELECT SUM(field1) AS sumvalue FROM table1` - 平均值：`SELECT AVG(field1) AS avgvalue FROM table1` - 最大值：`SELECT MAX(field1) AS ...
**1. 查询** 在LINQ to SQL中，你可以通过实例化一个DataContext类来访问数据库中的表。例如： ```csharp DBContext dc = new DBContext(); var s = from t1 in dc.Table1 select t1; ``` 这将返回`Table1`表中的...
* 总数：SELECT COUNT(*) AS totalcount FROM table1 * 求和：SELECT SUM(field1) AS sumvalue FROM table1 * 平均：SELECT AVG(field1) AS avgvalue FROM table1 * 最大：SELECT MAX(field1) AS maxvalue FROM ...
- **总数**：`SELECT COUNT(*) AS totalcount FROM table1`计算记录数。 - **求和**：`SELECT SUM(field1) AS sumvalue FROM table1`计算字段总和。 - **平均值**：`SELECT AVG(field1) AS avgvalue FROM table1`...
* 总数：select count as totalcount from table1 * 求和：select sum(field1) as sumvalue from table1 * 平均：select avg(field1) as avgvalue from table1 * 最大：select max(field1) as maxvalue from ...
- `SELECT COUNT(*) AS totalcount FROM table1`计算记录总数。 - `SELECT SUM(field1) AS sumvalue FROM table1`计算字段的总和。 - `SELECT AVG(field1) AS avgvalue FROM table1`计算字段的平均值。 - `...
- **计数**：`SELECT COUNT(*) AS totalcount FROM table1` - **求和**：`SELECT SUM(field1) AS sumvalue FROM table1` - **平均值**：`SELECT AVG(field1) AS avgvalue FROM table1` - **最大值**：`SELECT ...
- `SELECT COUNT(*) AS totalcount FROM table1` 计算记录数。 - `SELECT SUM(field1) AS sumvalue FROM table1` 求和。 - `SELECT AVG(field1) AS avgvalue FROM table1` 计算平均值。 - `SELECT MAX(field1) ...
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count函数是用来统计表中或数组中记录的一个函数，count(*) 它返回检索行的数目， 不论其是否包含 NULL值。最近感觉大家都在讨论count的区别，那么我也写下吧：欢迎留言讨论，话不多说了，来一起看看详细的介绍吧。 ...
计数问题：在 SQL Server 中，COUNT 函数对包含空值的一个列进行计数时，空值会从计算中消除。但假如 COUNT 函数使用一个星号，它就计算所有行，而不管是否存在空值。如果希望 COUNT 函数对给定列的所有行（包括空值...
+CAST((SELECT col2FROM tbWHERE col1=a.col1AND col2NOT IN(MAX(a.col2),MIN(a.col2)))as varchar) ELSE '' END +CASE WHEN COUNT(*)>=2 THEN ','+CAST(MAX(col2)as varchar) ELSE '' END FROM tb a GROUP ...
- **COUNT**：计算行数，`SELECT COUNT(*) AS totalcount FROM table1`。 - **SUM**：求和，`SELECT SUM(field1) AS sumvalue FROM table1`。 - **AVG**：计算平均值，`SELECT AVG(field1) AS avgvalue FROM ...
- 总数：`SELECT COUNT(*) AS totalcount FROM table1` - 求和：`SELECT SUM(field1) AS sumvalue FROM table1` - 平均值：`SELECT AVG(field1) AS avgvalue FROM table1` - 最大值：`SELECT MAX(field1) AS ...
**1. 查询** 在LINQ to SQL中，你可以通过实例化一个DataContext类来访问数据库中的表。例如： ```csharp DBContext dc = new DBContext(); var s = from t1 in dc.Table1 select t1; ``` 这将返回`Table1`表中的...
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* 总数：SELECT COUNT(*) AS totalcount FROM table1 * 求和：SELECT SUM(field1) AS sumvalue FROM table1 * 平均：SELECT AVG(field1) AS avgvalue FROM table1 * 最大：SELECT MAX(field1) AS maxvalue FROM ...
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- **总数**：`SELECT COUNT(*) AS totalcount FROM table1`计算记录数。 - **求和**：`SELECT SUM(field1) AS sumvalue FROM table1`计算字段总和。 - **平均值**：`SELECT AVG(field1) AS avgvalue FROM table1`...
* 总数：select count as totalcount from table1 * 求和：select sum(field1) as sumvalue from table1 * 平均：select avg(field1) as avgvalue from table1 * 最大：select max(field1) as maxvalue from ...
- **总数**：`SELECT COUNT(*) AS totalcount FROM table1`计算行数。 - **求和**、**平均**、**最大**、**最小**：使用聚合函数`SUM()`, `AVG()`, `MAX()`, `MIN()`。 11. **高级查询运算词**： - **UNION**：...
- `SELECT COUNT(*) AS totalcount FROM table1`计算记录总数。 - `SELECT SUM(field1) AS sumvalue FROM table1`计算字段的总和。 - `SELECT AVG(field1) AS avgvalue FROM table1`计算字段的平均值。 - `...
在SQL Server中，可以使用`sp_addumpdevice`存储过程添加备份设备，如`EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat'`，然后用`BACKUP DATABASE`命令进行数据库备份，如`BACKUP ...
- **计数**：`SELECT COUNT(*) AS totalcount FROM table1` - **求和**：`SELECT SUM(field1) AS sumvalue FROM table1` - **平均值**：`SELECT AVG(field1) AS avgvalue FROM table1` - **最大值**：`SELECT ...
- `SELECT COUNT(*) AS totalcount FROM table1` 计算记录数。 - `SELECT SUM(field1) AS sumvalue FROM table1` 求和。 - `SELECT AVG(field1) AS avgvalue FROM table1` 计算平均值。 - `SELECT MAX(field1) ...
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