Preface：Originally started with the internship，I never develop the habit of taking notes，But later I saw that my boss worked8It's been a year，I've been taking a lot of notes，Suddenly I've been entrusted，Here are my notes that I have recorded after changing，Hope it will be helpful to everyone.
0. As for me：No matter it isIntelliJ IDEA still eclipse, Font use Consolas, Font shape is regular, size: Xiao Wu ( IDEA 13 size),
at the same time IDEA of shortcut key Too eclipse, Specific settings file - setting - key map - eclipse - ok.
1. Implicit super constructor Object() is undefined for default constructor. Must define an explicit constructor
Solution：BundlejavaThe class library is loaded into，Right-click on the project to select properties->Java Build PathofLibraries->Add LibrarychooseJRE System Library->ClickNext->chooseExecution environment并choose版本或workspace default jre->ClickFinish。
2. Clone failed: Could not read from remote repository.
useIEDA Cloning failed, Usually there is no local installationgit
3. eclipse Open git
window - show view - other - searchgit - Click git repository - 然后Click克隆就行
4. IntelliJ IDEA Column Edit
File - setting - key Map - search column selection mode - Change to alt+shift+a (Pure personal habit).
5. eclipse console log Unlimited
window - preference - run/debug - console - Bundlelimit console output Remove the hook in front
6. eclipse console The text size of the column editing is different from the text size of the current editing box
window - preference - General - Appearance - color and fonts - search Text Editor Block Selection Font - edit
7. IDEA Width of the line
File->settings->Code Style->Generalmiddle，Revise“Right margin (columns)”The value of the code line width can be changed。
8. eclipse Width of the line
Window->Preferences->Java->Code Style->Formatter Find in the right windowEdit .turn upLine Wrapping . existMaximum line width Set width in the middle（I set it200，Feeling more appropriate, Ha ha ha ha ~ ）
9. eclipse
D:\tools\eclipse\dropins Localeclipse Plugin path (Temporarily understand dropins It's the plugin folder)
.i18n.resourcebundle_0.8.0 ResourceBundle EditorPlugin ：Select a file - Right-click to edit - open with - other - Resource File Editor that is ResourceBundle EditorPlugin
.tomcat_3.3.0 Externaltomcat ： alt+t Can be started directlytomcat
subclipse svn
openexplorer_100.jar In the project,You can select the current file/Folders,You can open the local directory directly
10. maven
Install
help - install new software- Upper right corner Clickadd - name: m2e / location: /technology/m2e/releases
Note ：if Installmaven A conflict occurs, 比如以前Install失败过，Then there will be two options，Just choose Just merge and modify the one.
error
Failure to transfer :maven-jar-plugin:pom:2.3.2 from .......Maven If the plug-in is installed,
Clickeclipse of window - preferences - Maven - user settings . Can get thismavenof根目录. Find the root directory below Just include lastupdate of字样, No matter what still -jar.All count。
Find its previous level/Up to the previous level directory，Then delete, Then right-click the project - maven - update project. ok
11. Log4j cannot find properties file in a simple application
Add to document
The content is：(For reference only)
= debug, stdout
= .
=
= .
=[Project name] [%d{yyyy/MM/dd HH:mm:ss:SSS}][%C] %m%n
=warn
=warn
=warn
=warn
=warn
.v2=warn
=warn
=error
12. maven Project Importjar Bag
In this domain name Search what you wantjarBag /artifact/log4j/log4j/1.2.17
There will bemaven Configuration, Copy directly Just do
Or directlygoogle search maven slf4j-log4j12-1.7.21-sources repository
(Write what you need herejarBag)
13. IntelliJ IDEA Small editing window
file - setting - editor tabs
Tab limit : 55
14. alt+t eclipse start uptomcat
Change local tomcat D:\tools\apache-tomcat-7.0.64\conf In the directory
and document
The last line
<Context path= "web1" docBase="D:\java_eclipse\web1\WebContent" reloadable="false" crossContext="true" />
<!-- <Context path= "kms" docBase="D:\java_eclipse\web1\WebContent\WEB-INF" reloadable="false" crossContext="true" /> -->
15. Heap memory is used to storenewObjects and arrays created。
After an array or object is generated in the heap，You can also define a special variable in the stack，Let the value of this variable in the stack be equal to the first address of the array or object in heap memory，This variable in the stack becomes an array or pair Reference variables for an icon。
int a = 10;
(variable)Stack heap(new come out)
16. Probably the path to Git executable is not valid. Fix it.
No local installationgit
17. idea Import the project Report canoot resovle symbol 'alibaba' Anomalies like this
file - project structure - Left menu Modules - Sources、Path、Dependecies(Generally this is, It isjarBag), Delete the error and pour it in againjarBag就行.
18. :
Directly UnitDTO implements Serializable At onceokIt's
19. mysql Local installation
There are usually two installation windows。If only one, Then clickwindowskey, Then findmysql server instance config wizard This program, Then click on Install
20. eclipse Configuration Externaltomcat alt + t
: D:\tools\apache-tomcat-7.0.64\conf\ The configuration is as follows
<Context path= "demo" docBase="D:\java\demo\WebContent" reloadable="false" crossContext="true" />
path= "demo" : demo It's the name of the project
docBase="D:\java\demo\WebContent" : It's the absolute path to the project
If it can Go in But no other accessservlet, At once Right-click project - properties - Java Build Path - source in There is one at the bottom Browse Button。After clicking。SelectWebContentThe following WEB-INF Create aclasses Folders, Clickok
21. exception It is divided into compile-time exceptions and run-time exceptions, error A large error occurred.
22. Convert the score row data into columns
select name,
case when coach = 'a' then course end as a,
case when coach = 'b' then course end as b,
case when coach = 'c' then course end as c,
case when coach = 'd' then course end as d
from da;
23. mysql where id in Sort according toin的顺序Sort
1. select * from user_subject where id in(
2628,
2629,
3786
) order by field(
id,
2628,
2629,
3786
);
2. select * from user_subject where id in(
2628,
2629,
3786
) order by substring_index(
'2628,
2629,
3786',
id,
1
);
24. Error: Can't update: no tracked branch
No tracked branch configured for branch git. To make your branch track a remote branch call, for example,
git branch --set-upstream git origin/git
Solution： IDEA There is a lower right corner Git:master , Of course, it may not be the case when this error is reportedGit:master But Git:git Or Git:XXX , Click on it, current branch: Is it truemaster, If not,
Clicklocal branchThe following xxx , 再Click CheckOut Switch working directory, Thenxxx If the branch is useless, Just straightremove;
25. int[] arr = new int[0];
Compare directnullThe good thing is：Can avoid empty pointers。
26. style="resize: none;" Will textarea Immutable
27. centOS eclipse Can't addservers
1. closureEclipse
2. OpenWorkSpaceLocation。
{workspace-directory}/.metadata/.plugins//.settings
Delete the following file
3. Restart Eclipse，All problems can be solved。
28. could not load the tomcat server configuration at /servers/tomcat v7.0 server at localhost-config. the configruation may be corrupt or incomplete. -- Alwaystomcat（webproject）Can't run。
Currently unzippedtomcat The file configuration is corrupted。Download one directly，Re-decompression, Configure toeclipseJust do。Remember to damage the original onetomcatDelete。
29. checkbox Select
$('input[type="checkbox"]').change(function() {
alert ("The element with id " + + " -- " + + " changed.");
});
Number of selected: var num = $("input:checked").length;
SelectID-checkbox: $("#role1").attr("checked", true);//false
30. Below the application There is one programming ,programming里面There is one Eclipse 4.4.1 How to delete？
exist/usr/share/applications delete
ln -s /opt/eclipse/eclipse /usr/bin/eclipse It's a soft link
31. Front desk passid Pickselect When the value of, 如果一直Pick得是一样的那就有可能是下面这种情况:
<form:hidden path="gym_id" />
<form:select cssClass="form-control" path="gym_id" items="${gymList}" itemLabel="name" itemValue="id"></form:select>
Because there are two identical pages at the same timegym_id, So when you get the value, you always get the aboveid,
The solution is to Delete the useless one above,Just do.
32. The archive: C:/Program Files/Apache Software Foundation/Tomcat 7.0/bin/ which is referenced by the classpath, does not exist.
Because I'llwindow - perferenes - servers - runtime envionments - The insidetomcat The path fromC The disk has been changed Dplate。Causes this error。
Solution： Clickwindow - show view - servers - double click tomcat server - open launch configuration - classpath - user entries - 、、。 These threejarPackage，Then see if the path is correct，If the path is wrong or has a duplicate name, delete it。
33. eclipse Revise console Font size
Windows - Preferences - General - Appearance - Color and Font - Debug - Console font - edit - console conventional Xiao Wu
34. : Unknown property 'isFirstGym' on class 'class
It should be of this fieldget、setWritten wrong。isFirstGym Written FirstGym
35. connectRobomongo
file - content - create/edit - connection
- name : test
- address : 101.200.***.* : (port) : 33333
- authentication
Will perform authentication Selection box Check it
Database : *
user name : *
password : *
Auth Mechanism ：The selected is Default SCRAM-SHA-1
Finally click on the bottom left corner test - save
36. CancelformForm input Enter automatically submit
<input type="text" size="35" name="q" value="${}" placeholder="Please enter what you want to search for..." class="form-control input-sm" οnkeypress="javascript:return checkKeys();"/>
function checkKeys(){
if( == 13){
doSearch();
return false;
}
}
37. Front desk judgmentlist Empty <c:if test="${kkUserList != '[]'}">
38. <display:table name="articles" cellspacing="0" cellpadding="0" requestURI="" defaultsort="1" />
name="articles" : articles Yes belongs to From the backgroundlist
: article Can define it yourself，Equivalent to variables
<img src="${article.article_img}" width="50px"/>
src="${article.article_img}" : article.article_img In-house article Belongs to the above definition id, Not name
39. IntelliJ IDEA Cancel the number of console rows limit
Installation Directory ： C:\Program Files (x86)\JetBrains\IntelliJ IDEA Community Edition 2016.1.1\bin
existidea7The subsequent version was cancelled Console row count settings Options，Changes can only be made by changing the configuration file
exist%Installation Directory%/binFile found in，Changeidea．ＣThe item value isdisabled，save，RestartideaJust
40. Convert case
IDEA : ctrl + shift + u ( If not, Try it ctrl + shift + x / y )
eclipse : ctrl + shift + x / y
41. guava Join
uuid : String sql = "select name, uuid from user where uuid in ('" + ("','").join(list) + "') ";
id : String gymSql = "select name, id from gym where id in (" + (",").join(gymList) + ") ";
42. Convert long type to int type in java
1. Forced type conversion
[java]
long ll = 300000;
int ii = (int)ll;
2. Call the intValue() method
[java]
long ll = 300000;
int ii= new Long(ll).intValue();
3. First convert long into a string String, and then convert the line into an Integer
[java]
long ll = 300000;
int ii = ((ll));
43. select * from `topic` limit 0, 10;
The subscript starts from 0 and query 10 items;
44. js Uncaught SyntaxError: Unexpected identifier
{"share":{"share_url":"/page/bangyangdeliliangliyao","share_text":" There is only one difference between a fat girl and a goddess\"Quick\" The goddess speaks with facts","share_title":"18 pounds of meat, the goddess uses behavior to prove it"},"pic":"/upload/","type":"h5","url":"/page/bangyangdeliliangliyao"}
The "Quick" in this json has double quotes. So the meeting will be wrong
Just replace the controller's json: bannerJson = ("\\", "\\\\\");
45. array : length, list : size
js :
java :
()
()
var textImgArray = eval("(" + textImg + ")");
eval:
1. Convert an array of strings to jsonArray
var a = (imgArray[item]);
1. Convert json array into string
(uploadImgUrl); : Convert to json object
for loop
for ( var item in imgArray) {
jsonLength++;
}
46. Add pictures
function showPreviewImageSortArray(picJsonDataDivId, imgPreviewDivId) {
var gymPicStr = $("#" + picJsonDataDivId).val();
if (gymPicStr != '') {
$("#" + imgPreviewDivId).empty();
var picStr = convertEntities(gymPicStr);
var imgArray = eval("(" + picStr + ")");
for (var i = 0; i < ; i++) {
var imgElem = '<a class="example-image-link" style="position:relative;display: inline-block;" href="' + imgArray[i].original_pic + '" data-lightbox="example-set" >';
imgElem += '<img class="example-image" src="' + imgArray[i].thumbnail_pic + '" alt="" style="width:100px;" />';
imgElem += '</a> <input type="button" name="button'+i+'" value="Excerpt the picture" οnclick="buttonClick('+i+');"/><br>';
$(imgElem).appendTo($("#" + imgPreviewDivId));
}
}
}
function buttonClick(i){
var button_id = "button"+i; //Remove the current click button Id
if ($("#" + button_id).val()=='Fine the picture'){
$("#" + button_id).parents('#imgDiv').find('input').val('Fine the picture');
$("#" + button_id).val('Cancel fancy');
$("#" + button_id).parents('#imgDiv').find('.icon-jing').remove();
$("#" + button_id).prev().append('<em style="position:absolute;top:10px;right:10px; display:block;" class="icon-jing"><img src="<c:url value="/images/" />" width="20"></em>')
} else if ($("#" + button_id).val()=='Cancel flipping'){
$("#" + button_id).val('Fine the picture');
$("#" + button_id).parents('#imgDiv').find('.icon-jing').remove();
}
}
47. js
Tag: type="hidden"
Method: $("#a").hide();
.toFixed(1) Take 1 digit after the decimal point and round: toFixed() method rounds Number to the number of decimal places
//Take out the corresponding topic_uuid
var topic_uuid = $(this).attr('id');
48. When the page action value is not incorrect, the specified controller cannot be redirected. It may be that the value of an id or name in js cannot pass:
<input type="text" name="picAddJing"/>
<input type="text" name="pics"/>
49. Mongodb is bson, which can be parsed into json, but it is not json. Every key of it is a database field and cannot be added or deleted at will.
50. Java set directly converts to list
List<String> action_code_list = new ArrayList<String>();
action_code_list.addAll(set);
51. There are three tables in mysql, A/B/C, one column in the three tables is the same (comment), and add all the numbers in this column in the three tables in a statement.
select a+b+c from
(SELECT sum(comment) a FROM A)t1,
(SELECT sum(comment) b FROM B) t2,
(SELECT sum(comment) c FROM C) t3
52. Front-end: Page zoomed out, list will not have borders
theme-blue-gradient: class of the current page body
$(".theme-blue-gradient").attr("style","min-width:1420px;");
53. How to implement CentOS virtual machine and windows host to paste things with each other. [create_time: 2016-09-30 11:16, Host: Windows 7, Virtual machine: centOS 6.8]
1. Start the virtual machine.
2.
1. Shared text paste ---> Click on the device-shared paste board-two-way
2. Realize file sharing and pasting ---> Click on the device - drag and drop - two-way
3. This should be fine.
If not.
1. Turn off the virtual machine and start the Oracle VM VirtualBox Manager
2. Click Device - Storage - Controller: SATA, and select the selection box of "Using Host Input and Output (I/O) Cache".
3. Click Device - Storage - Controller: SATA - . Select the selection box of "Solid State Drive".
The last possibility is that there is no feature that enhances centOS
54. Change the linux root password. [create_time: 2016-09-30 11:21, Host: Windows 7, Virtual Machine: CentOS 6.8]
[e@localhost ~]$ su (write su or su -root here)
Password: (My current root password is 1)
[root@localhost e]# passwd (enter the command to change password)
Change the user root password.
New password: (Write a new password here. The following two sentences are that the verification password is too short. If it doesn’t matter, just press Enter.)
Invalid password: WAY is too short
Invalid password: Yes
Re-enter a new password:
passwd: All authentication tokens have been successfully updated.
[root@localhost e]# exit (is to exit the current root (user), return to the previous e (user))
55. IDEA edits java project
Add jar: Right-click the project - open module settings - libraries - Click " + " - Select the jar directory - Import - ok
The .java file should be the class icon: right-click the src package name - Mark directory As - source Root
Create the repository above github and use it
url: /randy-zs/kms_test ,
1. Add ssh-key public key to the repository,
I. Click General - Network Connections - SSH2 - Key Management - Generate RSA Key - If the local "C:\Users\Administrator\.ssh" does not have two files, id_rsa (private key) and id_rsa.pub (public key) below,
Just click on the lower right corner to save private key - ok,
II. Enter the "C:\Users\Administrator\.ssh" directory and copy the content of id_rsa.pub (public key). Put it in the github page Settings - SSH and GPG keys - new SSH key -
Title: (Write whatever you want)
Key: (the content of id_rsa.pub (public key))
Then click Add SSH key
2. Enter the github kms_test page, there is a clone and download on the right. Click it - then click on the upper right corner to use ssh - copy the address "git@:randy-zs/kms_test.git"
In idea - VCS - Checkout out from version control - Git clone down - select the right directory - ok.
3. If the idea file name is red. Click Project Name - VCS - GIT - Add - ok.
56. clone git project 没有project的 Directory structure and Various package names、Class Name
Will IDEA Submitted Project reset For the initial project : file - new - project - localcloneThe root directory of the project (like：D:\java_idea2\kms_test) - ok
57. When IDEA does not need to submit code for a certain folder or file
On the work path D:\java_idea\kms_test Created below .gitignore document
.gitignore of content
.idea
*.iml
.svn
*.jar
.project
.classpath
.settings
target
bin
*.cfe
*.cfs
*.si
/lucene/
.gitignore of content : It is equivalent to blocking all bring .jar of文件.
if .gitignore If this file doesn't work。。Delete the files that do not need to be uploaded first，Re-replace Just load it。
58. idea Lower left corner run todo Don't come out like that。 直接点Lower left corner的按钮就行.
59. Exportexcel
If purely numeric data is exported, And there is a green triangular mass in the upper left corner of the cell, Just nowset value When parse one time : .setCellValue((tele));
60. whenclone Down idea project The directory structure cannot be displayed、not available.
1. Right-click the project open Module Settings - Modules - If empty Click " + " Number import Module - All the waynext - When choosing a project Choose this Directory is a project in this format (D:\temp\kms_test)[src] - Then finish.
2. Then name Change to Same as the project name, Actually, it's mainly thisname and Root directory D:\temp\kms_test\out\production The followingname Same, 如果名称Same as the project name的话便于管理. - ok.
Modules - Name in of name, Must be and Root directory D:\temp\kms_test\out\production 下面of kms_test name一样, Otherwise the program Can't run, Will always report ClassNotFoundException.
Then in open Module Settings - libraries - Add so you wantjarBag.
61. windows Host linux(centOS) Virtual Machine Paste each other -- If not，It may not be installed with enhanced functions...
Start the virtual machine - equipment - Shared paste board - Two-way.
62. windows Host linux(centOS) Virtual Machine Shared folders -- If not，It may not be installed with enhanced functions...
ResearchedNMany days, Finally finished research...
I. sudo usermod -aG vboxsf e (This command is Will e Added by this user vboxsf In the group). vboxsf: Shared folders default Group name. This is the case all over the world, Don't ask why.
If prompted : The user is not heresudoersSolutions in files, Just leaveIIstep, If not, At onceokIt's.
II. Switch torootuser
[linux@localhost ~]$ su root
password：
[root@localhost ~]#
2
Check/etc/sudoersFile permissions，If read-only permission，Modify to writable permissions
[root@localhost ~]# ll /etc/sudoers
-r--r-----. 1 root root 4030 12moon 10 09:55 /etc/sudoers
[root@localhost ~]# chmod 777 /etc/sudoers
[root@localhost ~]# ls -l /etc/sudoers
-rwxrwxrwx. 1 root root 4030 12moon 10 09:57 /etc/sudoers
3
Revise/etc/sudoersdocument，Execute the command as follows：
/*username is your username*/
[root@localhost ~]# echo 'username ALL=(ALL) ALL' >> /etc/sudoers
orrootEnter under permissionsVisudo or vim /etc/sudoers,turn up root ALL=(ALL) ALLFields of,Add to the next line:
username ALL=(ALL) ALL
5Password expires in minutes,Need to re-enter next time,If you don't want to be so troublesome，The following methods can be used
username ALL=(ALL) NOPASSWD: ALL
illustrate：The format is{username Hosts in the network=（The target user who executes the command） Range of commands executed}
4
Save Exit，And restore/etc/sudoersThe access permissions are440
[root@localhost ~]# chmod 440 /etc/sudoers
[root@localhost ~]# ll /etc/sudoers
-r--r-----. 1 root root 4030 12moon 10 09:59 /etc/sudoers
5
Switch to normal user，Test user permission enhancement function
III. In the virtual machine system. Click equipment - Shared folders - choose Shared folders的路径、Fill in the name - choose Automatic hanging machine、Fixed allocation - ok.
IV. Restart Virtual Machine - ok .
Other: gpasswd -d e vboxsf (This command is Will e This user from vboxsf Delete in this group)
63. Beginners usegit Upload the code toCodingSimple steps. There are two methods in total,
The first one is to refer to the second one, Write it out yourself and use it. The second type is excerpted online. url: /gdfhp/p/ author: skyfhp
1. pass Git Bash Order, Enter the project root path.
git add .
git commit –m "First Submission"
git remote add origin git@:zhangdeshuai/kms_test.git
git push origin master (After this command is finished, you will enter itcodingCloud account password.)
account: .....
password: *****
ok..
2. I. Log in firstcodingWebsite registration account/
II. Log in to the newly registeredcodingaccount ,Add a project
Add a project—〉Enter a project name(chap1)—〉Enter a simple description of the project---〉choose"private"—〉Create a project
III. So far，The experiment needs to be included laterpushTo this projectchap1Down。
Here，Need to record/gdcs16_000/ （gdcs16_000Register your name，chap1For the created project name）
Can also be passedcodingwebsite，Select your project—〉Code，Can be found
IV. Installgit Client
Install firstGitsoftware：Git for Windowsdownload。// /
Detailed instructions during installation can be found
/vipzjyno1/article/details/22098621
V. Create a localgit storehouse
Create a folder on the local disk，Used to store requiredpusharrivecodingFile on。Open this folder，Right-click—〉 git bash here
enter
git init （After this operation is completed，A hidden folder will be generated.gitSuffix file）
VI. Add to、Submit files to local repository
Created just nowtestNewly created in the folder3A file，Add and submit these files to your local repository
Commands used：
git add . or git add <filename>
git commit –m "Project Description"
VII. Push local files tocodingserver
git remote add origin https:// /username/Project name.git
git push origin master
Summarize：
1>. Push Problems encountered in the process and how to deal with them
（1） ifpushNo permissions encountered，No prompts to enter the username and password directly403The problem
How to deal with it：Modify directly.git/configIn the fileurl：
https://codingusername:password@/username/Project name.git
Or by command：
git remote add origin https://codingusername:password@/username/Project name.git
（2）If it appears(non-fast-forward)mistake，
Can be used directly-f（Forced push）
git push –f origin master
Summarize the commands used，Mainly
git init
git add
git commit
git remote add origin /username/Project name.git
git push origin master
2>. aboutgitFor more detailed descriptions, please refer to the following documents
[1] CodingwebsitehelpIn-housegitCode Hosting
/help/faq/git/#git--git--codingnet
[2] gitTutorial（Liao Xuefeng's official website
/
[3] More detailedgitPrinciples and usage
/book/zh/v2
[4] git Easy guide
/p/git-guide/
64. How many bytes does an Enter key take up?
A Enter key=Two characters, Two characters=2Bytes, 2Bytes=2byte
65. Database: When the server database data is imported into the local database, Some table data cannot be imported correctly, Many errors have been reported.
It is mainly because the character set and sorting rules of the two databases are different, You can use the command to view the character set settings between two libraries, etc.. : show variables like 'character%';
If you want to change the character set and collation of the local database to the format of the server database, Remember to change the character set and sorting rules together, If only one of them is changed, Will report an error
servermysql Version5.5.28 -- Server version: 5.5.28-log MySQL Community Server (GPL)
Character Set:utf8 -- UTF-8 Unicode
Sorting rules:utf8_general_ci
If you have finished modifying the character set, you can still import some tables, Then it may bemysql The version is different.
66. mysql Query the current date7 Data from a day ago
Use it yourself:
select * from Table namewhere create_time > date_sub(curdate(),interval 7 day);
Other content:
change:/zmengj/p/ author : woWant to ride the wind
Assumption: Today is2016Year08moon01day.
date_sub('2016-08-01',interval 1 day) express2016-07-31
date_sub('2016-08-01',interval 0 day) express2016-08-01
date_sub('2016-08-01',interval -1 day) express2016-08-02
date_sub(curdate(),interval 1 day) express2016-07-31
date_sub(curdate(),interval -1 day) 2016-08-02
date_sub(curdate(),interval 1 month) express2016-07-01
date_sub(curdate(),interval -1 month) express2016-09-01
date_sub(curdate(),interval 1 year) express2015-08-01
date_sub(curdate(),interval -1 year) express2017-08-01
67. mysql group_concat Use
group_concat(id separator ',') as user_subject_id Usually withgroup by Use with
Normallygroup_concat This user will be associated withid Take it out, But if there iswhere Conditional words, It will filter it and then re-extract it
example:
select user_uuid, group_concat(id separator ',') as user_subject_id from Table namewhere expire_time > '2016-10-18' and all_times !=1 group by user_uuid;
68. uselinux Command CutmysqlLarge database backup file specified inuser_subject surface
linux system:
Assumptionskk_buz_20160701030001.sql In the shared folder, Enter this file, Right-click to open with terminal, Then execute the following command.
sed -n -e '/CREATE TABLE.*`user_subject`/,/UNLOCK TABLES/p' kk_buz_20160701030001.sql >7_user_subject.sql
The name of the table to be cut in the current foldersqlFile The name of the cut file
69.