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MySQL retrieve latest record for Group

左心房为你撑大大i 提交于 2020-01-28 07:13:40
问题 I have a social networking site and am struggling with a query. I have a posts table that holds all of the users posts and then a post_comments table that holds all comments on a post. I am trying to find the latest comment by post from post_comments table. The post_comments table has the following columns: post_comment_id, post_id, writer_user_id, post_comment_content, datetime I have grouped the results by post_id like so: SELECT * FROM post_comments GROUP BY post_id This almost does what I

MySQL retrieve latest record for Group

你说的曾经没有我的故事 提交于 2020-01-28 07:12:29
问题 I have a social networking site and am struggling with a query. I have a posts table that holds all of the users posts and then a post_comments table that holds all comments on a post. I am trying to find the latest comment by post from post_comments table. The post_comments table has the following columns: post_comment_id, post_id, writer_user_id, post_comment_content, datetime I have grouped the results by post_id like so: SELECT * FROM post_comments GROUP BY post_id This almost does what I

Bash: space in variable value later used as parameter

丶灬走出姿态 提交于 2020-01-28 06:59:24
问题 While writing a bash script to help creating polaroid thumbnail using Imagick's convert commmand. I encounter a problem. Although, I manage to work around with this (actually, because convert is flexible enough), I still want to know how to solve this without such specific workaround. So basically, the bash script will get a caption value which may contain space. I want to use that caption as parameter of convert . If the caption is empty (''), I will not use the option '-caption' for convert

Bash: space in variable value later used as parameter

久未见 提交于 2020-01-28 06:59:05
问题 While writing a bash script to help creating polaroid thumbnail using Imagick's convert commmand. I encounter a problem. Although, I manage to work around with this (actually, because convert is flexible enough), I still want to know how to solve this without such specific workaround. So basically, the bash script will get a caption value which may contain space. I want to use that caption as parameter of convert . If the caption is empty (''), I will not use the option '-caption' for convert

How to perform a natural sort in php using usort

落爺英雄遲暮 提交于 2020-01-28 06:51:16
问题 Does anyone know what the function is to perform a natural order sort using the usort function in PHP on an object. Lets say the object ($obj->Rate)has a range of values in $obj->10 $obj->1 $obj->2 $obj->20 $obj->22 What is I am trying to get the sort function to return $obj->22 $obj->20 $obj->10 $obj->2 $obj->1 As my current standard sort function function MySort($a, $b) { if ($a->Rate == $b->Rate) { return 0; } return ($a->Rate < $b->Rate) ? -1 : 1; } is returning $obj->1 $obj->10 $obj->2

git deploying project - file permissions - (chmod)

随声附和 提交于 2020-01-28 06:49:31
问题 I'm deploying my project with git to a remote server using a post-update hook. More specifically I'm following these steps. Everything on my local copy has the right permissions, however after deploying with git push production , files that are set to 777 change in the remote server to -rwxr-xr-x I've added to both (local/remote) .git/config the core variables filemode = false and I've changed as well my umask in /etc/profile to 0002 Any ideas why it keeps changing the mode of files? Thanks

How can scikit-learning perform PCA on sparse data in libsvm format?

空扰寡人 提交于 2020-01-28 06:47:45
问题 I am using scikit-learning to do some dimension reduce task. My training/test data is in the libsvm format. It is a large sparse matrix in half million columns. I use load_svmlight_file function load the data, and by using SparsePCA, the scikit-learning throw out an exception of the input data error. How to fix it? 回答1: Sparse PCA is an algorithm for finding a sparse decomposition (the components have a sparsity constraint) on dense data. If you want to do vanilla PCA on sparse data you

git deploying project - file permissions - (chmod)

我的未来我决定 提交于 2020-01-28 06:47:04
问题 I'm deploying my project with git to a remote server using a post-update hook. More specifically I'm following these steps. Everything on my local copy has the right permissions, however after deploying with git push production , files that are set to 777 change in the remote server to -rwxr-xr-x I've added to both (local/remote) .git/config the core variables filemode = false and I've changed as well my umask in /etc/profile to 0002 Any ideas why it keeps changing the mode of files? Thanks

Cocoa error 256 core data

纵然是瞬间 提交于 2020-01-28 06:46:59
问题 I have error "Cocoa error 256" when I try to save data. How to fix it? And what problem? 回答1: According to the help reference in Xcode: NSFileReadUnknownError Read error, reason unknown Available in Mac OS X v10.4 and later. Declared in FoundationErrors.h. Sadly, that's probably not too helpful, though it is an unknown -read- error. 回答2: If its a core data error there is probably an actual error object somewhere near where the error occurs. If you dump the error objects userInfo dictionary,

How to perform a natural sort in php using usort

社会主义新天地 提交于 2020-01-28 06:46:46
问题 Does anyone know what the function is to perform a natural order sort using the usort function in PHP on an object. Lets say the object ($obj->Rate)has a range of values in $obj->10 $obj->1 $obj->2 $obj->20 $obj->22 What is I am trying to get the sort function to return $obj->22 $obj->20 $obj->10 $obj->2 $obj->1 As my current standard sort function function MySort($a, $b) { if ($a->Rate == $b->Rate) { return 0; } return ($a->Rate < $b->Rate) ? -1 : 1; } is returning $obj->1 $obj->10 $obj->2

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