exists

centos7 无法启动网络(service network restart)错误解决办法:

由 混江龙づ霸主 提交于 2019-12-14 00:33:02
centos7 无法启动网络(service network restart)错误解决办法: 原博文：http://blog.csdn.net/zkja595470467/article/details/53007915 centos7 无法启动网络(service network restart)错误解决办法: (以下方法均为网上COPY,同时感谢原博主分享) systemctl status network.service 出现以下错误 “rtnetlink answers file exists” 的解决方法 第一种： 和 NetworkManager 服务有冲突，这个好解决，直接关闭 NetworkManger 服务就好了， service NetworkManager stop，并且禁止开机启动 chkconfig NetworkManager off 。之后重启就好了。(我使用第一种成功) 第二种：和配置文件的MAC地址不匹配，这个也好解决，直接修改 /etc/udev/rules.d/70-persistent-net.rules文件的MAC 地址和 /etc/sysconfig/network-scripts/ifcfg-eth0一样就好了。 (两种都不行的话可以试试这个) ip addr flush dev enoXXXXX (copy地址:http://www

MySQL 'if exists' error

由 可紊 提交于 2019-12-13 15:52:37
问题 I got a error in my MySQL query: if not exists(select * from tb_user where user_id=1) then select 'ok' as rul; else select 'not' as rul; end if; Where's my problem? 回答1: Another method: You may also use case when Select case when exists(select * from tb_user where user_id=1) then 'Ok' else 'Not' end ; * SQLFiddle Demo Sample table: ID NAME 1 john 2 tim 3 jack 4 rose Query: renamed the columns as Status Select case when exists(select * from table1 where id=1) then 'Ok' else 'Not' end as Status

MongoDB Aggregation SQL Union and SQL Exists like clause

由 你说的曾经没有我的故事 提交于 2019-12-13 06:49:47
问题 I would like to make a MongoDB aggregation Query on data like this : Collection A { _id : 1, Active : true, hasQuery : false, Running : false, } { _id : 2, Active : true, hasQuery : true, Running : false, } { _id : 3, Active : true, hasQuery : false, Running : true, } { _id : 4, Active : true, hasQuery : true, Running : true, } { _id : 5, Active : false, hasQuery : false, Running : false, } { _id : 6, Active : false, hasQuery : false, Running : true, } This JSON data could be represented by a

mysql not in or value=0?

由 南笙酒味 提交于 2019-12-13 03:02:01
问题 Database one is called widgets, it has "id" and "title". Database two is called widget-layouts and it has "module-id", "widget-id", "position", and "weight". What I am trying to do is check to see if widgets.id exists in widget-layout.widget-id and if it does, then does widget-layouts.position = 0. I also want to get the values of widgets that don't exist in widget-layouts. Here is the mysql query I have been working with. SELECT * FROM widgets, widget-layouts WHERE (widge-layouts.position =

Best practice to check if a variable exists in plpgsql?

由 夙愿已清 提交于 2019-12-13 02:57:40
问题 For instance I've got a stored procedure to import data from csv files and write the read data into a SQL table. I've got a table defined as below: CREATE TABLE person (id int, name text, age int, married boolean); First I check if the record exist already, if exists I do update, if doesn't - insert. Each field of record may have a different type, so the result of a SQL command are assigned to a list of scalar variables: SELECT name, age, married INTO v_name, v_age, v_married [..] Let's

Class exists in an external file

由 拟墨画扇 提交于 2019-12-13 02:42:27
问题 How do I check an external file for a class? I am trying to setup a install feature for my modules, so I am trying to get it to load a list of directories and then check if the module file has a method called install. So only the modules with this method will be shown in the list. Here is my code so far: $output .= '<div id="module-dialog" title="Add Widget"><form id="widget-list" name="widget-list"> <select name="widgets" size="12" id="widgets-list">'; $dirHandler = opendir('modules') or die

How would be the right way to use EXISTS clause

由 独自空忆成欢 提交于 2019-12-12 16:01:10
问题 In my SP I am creating a temp table #PolicyNumbers and populating it with Policy Numbers based on the parameters that will be supplied to the SP. CREATE TABLE #PolicyNumbers (PolicyNumber varchar(50)) INSERT INTO #PolicyNumbers SELECT PolicyNumber FROM PlazaInsuranceWPDataSet WHERE State IN (SELECT * FROM [dbo].[StringOfStringsToTable](@State,',')) AND Coverage IN (SELECT * FROM [dbo].[StringOfStringsToTable](@Coverage,',')) AND SICCode IN (SELECT * FROM [dbo].[StringOfStringsToTable](

Check for complete duplicate rows in a large table

由 这一生的挚爱 提交于 2019-12-12 09:56:45
问题 My original question with all the relevant context can be found here: Adding a multi-column primary key to a table with 40 million records I have a table with 40 million rows and no primary key. Before I add the primary key, I would like to check if the table has any duplicate entries. When I say duplicate entries, I don't just mean duplicate on particular columns. I mean duplicates on entire rows. I was told in my last question that I can do an EXISTS query to determine duplicates. How would

Rails: How to Select Records Which Don't Have a Specific Related (associated) Object (SQL EXISTS brief how-to)

由 我与影子孤独终老i 提交于 2019-12-12 09:20:25
问题 Let's assume we have users: class User < ActiveRecord::Base has_many :connections has_many :groups, through: :connections end And groups: class Group < ActiveRecord::Base has_many :connections has_many :users, through: :connections end Basically, standard many-to-many connection: class Connection belongs_to :user belongs_to :group end What I intend to do is: Select only users who don't belong to given set of Groups (groups with ids [4,5,6] ) Select only users who belong to one set of Groups (

How to Check if value exists in a MySQL database

由 ﹥＞﹥吖頭↗ 提交于 2019-12-12 07:08:26
问题 Suppose I have this table: id | name | city ------------------ 1 | n1 | c1 2 | n2 | c2 3 | n3 | c3 4 | n4 | c4 I want to check if the value c7 exists under the variable city or not. If it does, I will do something. If it doesn't, I will do something else. 回答1: preferred way, using MySQLi extension: $mysqli = new mysqli(SERVER, DBUSER, DBPASS, DATABASE); $result = $mysqli->query("SELECT id FROM mytable WHERE city = 'c7'"); if($result->num_rows == 0) { // row not found, do stuff... } else { //
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