问server计划缓存中的即席查询和准备查询之间有什么区别？

EN

select * from t1

select * from t1 where id=@id

command.CommandText = "SELECT * FROM users WHERE USERNAME = @username AND ROOM = @room";

    command.Parameters.AddWithValue("@username", username);
    command.Parameters.AddWithValue("@room", room);

select 
objtype,count(*) as countt,sum(size_in_bytes)*1024.0 as memoryinkb
 from   sys.dm_exec_cached_plans a
 group by objtype

select q.query_hash, 
    q.number_of_entries, 
    t.text as sample_query, 
    p.query_plan as sample_plan
from (select top 20 query_hash, 
            count(*) as number_of_entries, 
            min(sql_handle) as sample_sql_handle, 
            min(plan_handle) as sample_plan_handle
        from sys.dm_exec_query_stats
        group by query_hash
        having count(*) > 1
        order by count(*) desc) as q
    cross apply sys.dm_exec_sql_text(q.sample_sql_handle) as t
    cross apply sys.dm_exec_query_plan(q.sample_plan_handle) as p

DECLARE @MB decimal(19,3)
        , @Count bigint
        , @StrMB nvarchar(20)


SELECT @MB = sum(cast((CASE WHEN usecounts = 1 AND objtype IN ('Adhoc', 'Prepared') THEN size_in_bytes ELSE 0 END) as decimal(12,2)))/1024/1024 
        , @Count = sum(CASE WHEN usecounts = 1 AND objtype IN ('Adhoc', 'Prepared') THEN 1 ELSE 0 END)
        , @StrMB = convert(nvarchar(20), @MB)
FROM sys.dm_exec_cached_plans


IF @MB > 10
        BEGIN
                DBCC FREESYSTEMCACHE('SQL Plans') 
                RAISERROR ('%s MB was allocated to single-use plan cache. Single-use plans have been cleared.', 10, 1, @StrMB)
        END
ELSE
        BEGIN
                RAISERROR ('Only %s MB is allocated to single-use plan cache – no need to clear cache now.', 10, 1, @StrMB)
                — Note: this is only a warning message and not an actual error.
        END
go