SQL 查询根据条件计算行数？不断收到我的计数逻辑的语法错误

Question

select sum(bookID) as totalbooks, count(bookstatus = R) as returnedbooks
from library with (nolock)
where 
   librarylocation = 'Chesterfield'
   --and bookstatus = R

所以我希望我的查询 return 一列总共有多少本书，但是 return 一列有多少本书。我正在使用 count 也应用条件，但我收到错误消息：

Incorrect syntax near ')'.

无论如何要实现这个？

Answer 1

这里是语法错误count(bookstatus = R)

你可以像下面这样转换

select sum(bookID) as totalbooks, SUM(CASE WHEN bookstatus = R THEN 1 ELSE 0 END) as returnedbooks
from library with (nolock)
where librarylocation = 'Chesterfield'
--and bookstatus = R

SQL 查询根据条件计算行数？不断收到我的计数逻辑的语法错误

SQL query to count rows based on condition? Keep getting syntax error for my count logic

sql

tsql

sql-server

sum

count