列出 SQL 中每个字段值的行数
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List number of rows per field value in SQL
提问by Brennan Vincent
database/SQL novice here.
数据库/SQL 新手在这里。
I have a table with a column called, for example, "EmployeeID". I want a query that will, for each distinct employeeID, return the number of rows that have that as their ID. I hope it's clear what I'm trying to do and someone will know how to help!
我有一个表，其中有一列名为“EmployeeID”。我想要一个查询，该查询将为每个不同的员工 ID 返回以该 ID 作为 ID 的行数。我希望很清楚我要做什么，并且有人会知道如何提供帮助！
I don't think it should matter, but just in case, I'm using MS SQL Server 2008.
我认为这无关紧要，但以防万一，我使用的是 MS SQL Server 2008。
回答by josephj1989
Simple SQL
简单的 SQL
select EmployeeId,count(*)
from YourTable
Group by EmployeeId
回答by OMG Ponies
Use:
用：
SELECT t.employeeid,
COUNT(*) AS num_instances
FROM TABLE t
GROUP BY t.employeeid
COUNT is an aggregate function, which requires the use of a GROUP BY clause.
COUNT 是一个聚合函数，它需要使用 GROUP BY 子句。
回答by Martin Smith
select count(*) AS RowCount, EmployeeID
FROM table
GROUP BY EmployeeID
回答by Abe Miessler
This should do the trick:
这应该可以解决问题：
SELECT employeeID, COUNT(employeeID) FROM Employees GROUP BY employeeID
回答by flayto
SELECT DISTINCT employeeID,
COUNT(employeeID) AS [Count]
FROM Employees
GROUP BY employeeID
