直接执行下面语句进行查询即可,WHQJAccountsDB替换成你要备份的数据库名,

C:\bak\替换成你要保存备份文件的路径

use master;  
go
--文件日期后缀
declare @prefix nvarchar(100) = convert(varchar(50),getdate(),112) +'_'+ DateName(hour,GetDate())+DateName(minute,GetDate()) +DateName(second,GetDate())+'.bak'
declare @dbName nvarchar(100)='WHQJAccountsDB'; --数据库名
declare @dbFullName nvarchar(150)='C:\bak\'+ @dbName +'_'+ @prefix; --备份路径

DECLARE @kid varchar(200)
SET @kid=''
--生成终结数据库进程语句
SELECT @kid= @kid + ' KILL '+CAST(spid as Varchar(10)) FROM master..sysprocesses WHERE dbid=DB_ID(@dbName)
PRINT @kid
EXEC(@kid); --执行终结数据库进程
backup database @dbName to disk=@dbFullName; --备份数据库