更快地更新peakpowerforchannel(faster updating of peakpowerforchannel)
我正在使用NSTimer来更新iphone的峰值功率。 从监控来看,它不会非常快速地更新。 我需要以100微秒(100us)的顺序更新峰值功率的高频率。 我也尝试使用usleep(100)每100us更新一次。 还是很慢。 有人可以帮我指出如何实现这一目标吗? 我想我需要使用此代码来测量距离。 谢谢。
I am using NSTimer to update peak power from iphone. From monitoring, it does not update very fast. I need high frequency of updating peak power in order of 100 micro second (100us). I also try with usleep(100) to update every 100us. Still very slow. Can someone help me to point out how to achieve this? I am thinking I need to use this code to measure distance. Thank you.
原文:https://stackoverflow.com/questions/5800527
最满意答案
你需要从
person
而不是animals
获得id字段。取单独的ID
field
。$sql = "SELECT *, h.id as pid FROM person h LEFT JOIN animals o ON o.name = h.name";
PHP中的变化:
foreach ($pdo->query($sql) as $row) { echo $row['pid']; echo $row['animal']; }
You need to get id field from
person
notanimals
.Fetch separate id
field
.$sql = "SELECT *, h.id as pid FROM person h LEFT JOIN animals o ON o.name = h.name";
Change in PHP:
foreach ($pdo->query($sql) as $row) { echo $row['pid']; echo $row['animal']; }
相关问答
更多-
MySQL - 如何使用(LEFT)JOIN通过一个表连接两个表?(MySQL - How to use (LEFT) JOIN to join two tables via one table together?)[2024-04-10]
SELECT l.name, p.id FROM link l LEFT JOIN person_link pl ON (l.id = pl.id_link) LEFT JOIN person p ON (pl.id_person = p.id && l.id = pl.id_link && p.id = 2) group by l.link 或者基于Nirala的回答 SELECT l.name, pl.id_person FROM link l LEFT JOIN person_ ... -
MYSQL:使用一个表中的不同值左连接两个表(MYSQL: left join in two tables using distinct value from one table)[2022-09-30]
更改: FROM tempsubstation ts 至: FROM (SELECT * FROM tempsubstation GROUP BY columnWithDuplicateValues) ts Change: FROM tempsubstation ts to: FROM (SELECT * FROM tempsubstation GROUP BY columnWithDuplicateValues) ts -
查看你的模式和你的预期结果似乎你需要这个查询 select a.ID, a.omschrijvingID, b.omschrijving, sum(c.aantal), a.min from omschrijvingVoorraad as a inner join omschrijving as b on a.omschrijvingID = b.ID inner join voorraad as c on a.omschrijvingID = c.omschrijvingID group by a.ID, ...
-
为列名使用别名来区分团队表和玩家表中具有相同名称的列。 SELECT teams.id as team_id, teams.name as team_name, players.id, players.name, players.teamId FROM teams LEFT JOIN players ON teams.id = players.zoneId WHERE teamId = 3 然后你可以使用下面的来获取球队名称和球队ID: $row["team_name"] $row["team_id"] ...
-
使用IS NULL : SELECT PLAYERS.*, TYPES.GUEST_ID FROM PLAYERS LEFT JOIN TYPES ON TYPES.GUEST_ID = PLAYERS.GUEST_ID WHERE TYPES.GUEST_ID NOT IN('1', '2') OR TYPES.GUEST_ID IS NULL Use IS NULL: SELECT PLAYERS.*, TYPES.GUEST_ID FROM PLAYERS LEFT JOIN TYPES O ...
-
我非常抱歉浪费你的时间,经过彻底的重新检查,我发现我的表数据是错误的(在制作sqlfiddle之后检查@Barmar)。 我错误地在like和comment表中插入了错误的数据。 因此,对于第二个主题topicid='2'的groupid='1'喜欢和评论被错误地插入了topicid='1' ,这就是为什么细节只在第一个主题中显示而没有出现在第二个主题。 上面的SQL是绝对正确的,并且谢谢你帮助我找到错误。 非常抱歉再次发布。 I am very very sorry for wasting your ti ...
-
那么,您已经发现将独立值保存为逗号分隔字符串的痛苦。 如果可以的话,我建议你改变你的数据结构,从用户表中获取专业列,然后创建一个新的user_specialty表,该表的外键可以是users.username和tasks.tags 。 +----------+------------------+ | username | tag | +----------+------------------+ | JinkX | php | | JinkX ...
-
如何连接mysql中两个不同表的数据(LEFT JOIN)?(How can I connect data from two different tables in mysql (LEFT JOIN)?)[2022-05-16]
你需要从person而不是animals获得id字段。 取单独的ID field 。 $sql = "SELECT *, h.id as pid FROM person h LEFT JOIN animals o ON o.name = h.name"; PHP中的变化: foreach ($pdo->query($sql) as $row) { echo $row['pid']; echo $row['animal']; } You need to get id field from ... -
使用EJBQL的LEFT JOIN表(LEFT JOIN tables with EJBQL)[2022-11-26]
如果两者之间没有关系,并且如果你真的只需要Machine对象,你可以做的是将LEFT JOIN FETCH更改为IN语句,如(伪代码): select from Machine m where (SUBSTRING(m.hostname, 1, :length) in (some kind of logic about Location) If there is no relation between the two, and if you really only need the Machineobj ... -
纯SQL解决方案: SELECT res.id, res.project, GROUP_CONCAT(res.singer) as singer, GROUP_CONCAT(res.musician) as musician, GROUP_CONCAT(res.actor) as actor FROM ( SELECT prj.id as id, prj.title as project, IF(ppl.position = 'singer', ppl.name, null) ...