sqlserver语句计数
时间: 2023-07-30 10:08:30 浏览: 44
SQL Server 分页查询的 SQL 语句如下:
```
SELECT *
FROM (
SELECT ROW_NUMBER() OVER (ORDER BY [column_name]) AS RowNumber, *
FROM [table_name]
) AS t
WHERE RowNumber BETWEEN [start_number] AND [end_number]
ORDER BY [column_name];
```
请注意:
- `[table_name]` 需要替换为实际表名。
- `[column_name]` 需要替换为排序的列名。
- `[start_number]` 和 `[end_number]` 分别表示分页的开始和结束行号。
相关问题
sql server 去重计数
要在SQL Server中进行去重计数,可以使用以下查询语句:
SELECT COUNT(DISTINCT [Mobile]) as UniqueCount
FROM [dbo].[Campaigns]
这个查询语句将返回一个名为UniqueCount的列,其中包含去重后的手机号数量。<span class="em">1</span>
#### 引用[.reference_title]
- *1* [SqlServer 数据去重](https://blog.csdn.net/weixin_33701251/article/details/86249927)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_2"}}] [.reference_item style="max-width: 100%"]
[ .reference_list ]
SQL server语句建立学生选课数不超5门的触发器
下面是SQL Server语句建立学生选课数不超过5门的触发器:
```sql
CREATE TRIGGER tr_check_course_count
ON student_course
AFTER INSERT, UPDATE
AS
BEGIN
DECLARE @student_id INT;
DECLARE @course_count INT;
SELECT @student_id = student_id, @course_count = COUNT(*)
FROM student_course
WHERE student_id IN (SELECT student_id FROM inserted)
GROUP BY student_id;
IF @course_count > 5
BEGIN
RAISERROR ('The student has exceeded the maximum course count of 5.', 16, 1);
ROLLBACK TRANSACTION;
END
END
```
该触发器会在`student_course`表中插入或更新记录后执行。它首先检索所有刚插入或更新的学生ID,并计算他们选择的课程数量。如果任何一个学生选择的课程数量超过5,触发器将抛出一个错误并回滚事务,防止该学生选择更多的课程。请注意,触发器假定每个学生只能选择一次课程,如果允许学生多次选择同一课程,则需要对计数逻辑进行修改。