大约有 42,000 项符合查询结果（耗时：0.0300秒） [XML]
Which is fastest? SELECT SQL_CALC_FOUND_ROWS FROM `table`, or SELECT COUNT(*)
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It depends. See the MySQL Performance Blog post on this subject: To SQL_CALC_FOUND_ROWS or not to SQL_CALC_FOUND_ROWS?
Just a quick summary: Peter says that it depends on your indexes and other factors. Many of the comments to the post seem to...
App Inventor 2 人脸识别App开发 - 第三方API接入的通用方法 · App Inventor 2 中文网
...建一个应用以获得API调用时必要的api_key及api_secret。
如何理解api_key及api_secret：可以类比为 API Key是用户ID（用于标识用户），Secret Key是密码（用于鉴权）。“你需要两个不同的密钥，一个告诉他们你是谁，另一个证明你就是...
常用Git命令汇总 - 开源 & Github - 清泛网 - 专注C/C++及内核技术
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#改变暂存区的修改（其实是重置HEAD，将指定版本库的内容状态去覆盖暂存区，从而达到暂存区的改变）
git reset <file> #从暂存区恢复到工作区（不指定版本id，则默认为最后一次提交的版本id）
git r...
How do I kill all the processes in Mysql “show processlist”?
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You need to kill them one by one, MySQL does not have any massive kill command. You can script it in any language, for example in PHP you can use something like:
$result = mysql_query("SHOW FULL PROCESSLIST");
while ($row=mysql_fetch_array($result)) {
$pro...
mysql error 1364 Field doesn't have a default values
...does not address the root cause either because the root cause was a bug in MySQL that was fixed in v5.7.1 - see the answer by B98: stackoverflow.com/a/29854279/5389997 Removing strict_trans_table sql mode makes MySQL more prone to data quality errors, so removing it is not a really good advice.
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SQL how to make null values come last when sorting ascending
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@Martin Note this question is not tagged mysql. I provided a generalized solution - there are many different ways of doing the same thing across different dbs.
– RedFilter
Oct 16 '15 at 14:15
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Difference between natural join and inner join
... definition of a natural join is to join on *all like-named columns*. From MySQL doc: The NATURAL [LEFT] JOIN of two tables is defined to be semantically equivalent to an INNER JOIN or a LEFT JOIN with a USING clause that names all columns that exist in both tables.. And another thing - in practice ...
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
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So, you have a
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
java.net.ConnectException: Connection refused
I'm quoting from this answer which also contains a step-by-step MySQL+JDBC tutorial:
If yo...
Suppress warning messages using mysql from within Terminal, but password written in bash script
When I tried running the following command on MySQL from within Terminal:
25 Answers
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error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' — Miss
...roblem started off with me not being able to log in as root any more on my mysql install. I was attempting to run mysql without passwords turned on... but whenever I ran the command
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