count(1), count(*), count(column)区别 count(1)和count(*)是相同的, 但count(*)代表的语义更明确 COUNT(<expression>) 统计非空值个数 使用IN时是

查找lock select * from master.dbo.sysprocesses where DB_NAME(dbid)=’test’ and spid<>@@SPID; exec sp_lock exec sp_who2 SPID; select request_session_id, resource_type, resource_description, request_mode, request_status, request_owner_type from sys.dm_tran_locks; kill SPID; 查看表结构 SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'yourTableName'; 日期 -- 当前时