alias

python sqlalchemy label usage

由 ぃ、小莉子 提交于 2019-12-17 16:15:41
问题 I know I can use the label method for alias, but I can't figure out how to use the labeled element later in the query - something like the following: session.query(Foo.bar.label("foobar")).filter(foobar > 10).all() Of course, this doesn't work since there is no variable called foobar. How could this be accomplished? (The over simplified example was just for easy comprehension...) 回答1: Offhand, I believe you can use the labeled column itself as an expression: foobar = Foo.bar.label("foobar")

How to use aliases defined in .bashrc in other scripts?

由 我与影子孤独终老i 提交于 2019-12-17 10:57:15
问题 In ~/.bashrc, I defined some aliases. But I cannot use them in other shell scripts, where I can only use aliases defined right there. Even though I sourced bashrc, it still did not work. What should I do? PS. I'm in bash. 回答1: You need to do shopt -s expand_aliases in the script in addition to sourcing ~/.bashrc . 回答2: I had this problem and I reloaded the file with this command to fix it. $ source ~/.bashrc 回答3: The simplest answer is to do the 2 important things or it wont' work. #!/bin

PostgreSQL does not accept column alias in WHERE clause

由 ≯℡__Kan透↙ 提交于 2019-12-17 09:59:21
问题 In this pgexercises about joining 3 different tables, the answer is given as following: select mems.firstname || ' ' || mems.surname as member, facs.name as facility, case when mems.memid = 0 then bks.slots*facs.guestcost else bks.slots*facs.membercost end as cost from cd.members mems inner join cd.bookings bks on mems.memid = bks.memid inner join cd.facilities facs on bks.facid = facs.facid where bks.starttime >= '2012-09-14' and bks.starttime < '2012-09-15' and ( (mems.memid = 0 and bks

How to alias a field or column in MySQL?

由 女生的网名这么多〃 提交于 2019-12-17 07:21:47
问题 I'm trying to do something like this. But I get an unknown column error: SELECT SUM(field1 + field2) AS col1, col1 + field3 AS col3 from core Basically, I want to just use the alias so that I won't need to perform the operations performed earlier. Is this possible in mysql? 回答1: Consider using a subquery, like: SELECT col1 , col1 + field3 AS col3 FROM ( SELECT field1 + field2 as col1 , field3 from core ) as SubQueryAlias 回答2: select @code:= SUM(field1 + field2), @code+1 from abc; But, please

How do I assign an alias to a function name in C++?

由 随声附和 提交于 2019-12-17 03:51:24
问题 It's easy to create a new name for a type, a variable or a namespace. But how do I assign a new name to a function? For example, I want to use the name holler for printf . #define is obvious... any other way? Solutions: #define holler printf void (*p)() = fn; //function pointer void (&r)() = fn; //function reference inline void g(){ f(); } 回答1: There are different approaches: With C++11 with non-template non-overloaded functions you can simply use: const auto& new_fn_name = old_fn_name; If

我的 .zshrc 配置备份

由 ﹥＞﹥吖頭↗ 提交于 2019-12-14 09:20:16
# If you come from bash you might have to change your $PATH. # export PATH=$HOME/bin:/usr/local/bin:$PATH alias log_project_neibu = "ssh -t log_dev_143 'cd /tol/logs/kooup-dubbo-project-neibu; bash'" alias log_pc_student_neibu = "ssh -t log_dev_143 'cd /tol/logs/kooup-webapp-student-neibu; bash'" alias log_mobi_student_neibu = "ssh -t log_dev_143 'cd /tol/logs/kooup-webapp-mobile-student-neibu; bash'" export M2_HOME = /Users/yakuiguo/dev/mvn/maven export PATH = $PATH : $M2_HOME /bin # Path to your oh-my-zsh installation. export ZSH = "/Users/yakuiguo/.oh-my-zsh" # Set name of the theme to load

Linux常用命令使用格式

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-14 07:45:59
例如echo、screen、date、ifconfig、export、alias等 echo： 先确定是内部命令还是外部命令，后查看帮助，大致意思，将写的参数输出至标准输出。 格式： echo [-neE] [arg …] 其中[]代表可以省略的意思，默认有一个换行符/n 其中默认选项是-E，代表默认抑制转译符，-e代表默认不抑制转义符，所以可以其中可以打印颜色： 格式:echo -e “\033[字背景颜色;文字颜色m字符串\033[0m”: screen: 事先要先安装一下screen 同样的步骤，后使用man命令查看帮助: 一开始看懂可以先翻译，或者直接百度一下screen命令用法，主要在-S 创建新的会话和-x 加入会话，可以使用-ls或-list查看screen有哪些会话。 创建一个会话,然后使用另一个终端加入进去，那么操作就可以同步了。 //两个要连接同一个主机，不通虚拟终端才可以使用这样，然后别人操作你主机就可以看到了 如果加入放想要临时退出的话，偷偷的查询一下命令的使用方法，可以使用ctrl+a按住+d可以临时退出会话，然后在用-x进入，在此之间，对方看不到你所做的任何操作： date 通过查看发现，此命令是用来查看给定的格式显示当前的时候，或者设置系统时间。 默认可以显示当前的系统时间，也可以指定格式显示系统时间：

Always start ipython with pylab being equal to inline, but toggle it off at some time

由 心不动则不痛 提交于 2019-12-14 04:18:50
问题 Is there any convention or configuration setting for how to start IPython shell? For example, when I start IPython, I almost always start it with pylab --inline . One approach is to create an alias, such as alias ipython="ipython --pylab inline" . However, I think it's impossible to start the shell with different options (other than inline option) once I decide to create and use the alias. So is it feasible to always start the shell with pylab=inline option, but still to toggle it off

How should I use the alias_method_chain for the build method?

由 末鹿安然 提交于 2019-12-14 03:56:56
问题 I am using Ruby on Rails 3.2.13 and I would like to properly use the alias_method_chain :build, :option_name statement since I am getting a strange error. That is, ... ... in my controller file I have: class Articles::CommentsController < ApplicationController def create @articles_comment = @article.comments.build(params[:comment]) ... end end ... in my model file I have: class Articles::Comment < ActiveRecord::Base def self.build_with_option_name ... end alias_method_chain :build, :option

when i was using find_by_sql alias, i got confused

由 谁都会走 提交于 2019-12-14 03:43:03
问题 I'm using RoR and mysql database. I want to convert timestamp column to string, so i have the SQL: @books = Book.find_by_sql("select id, name, date_format(borrow_date, '%m/%d/%Y') borrow_date from books") @books[0].borrow_date => 'Sun, 03 Aug 2014 17:00:00 PDT -07:00' When i output the borrow_date like @books[0].borrow_date, i got un-formatted string 'Sun, 03 Aug 2014 17:00:00 PDT -07:00' which is not expected. I want "08/03/2014" If i change alias name that different than the column name, i
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