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The data for the persons document is as follows:> Db.persons.find (){"_id": 2, "Name": 2}{"_id": 3, "Name": 3}> db.persons.update ({_id:4},{_id:4,name:4})Writeresult ({"nmatched": 0, "nupserted": 0, "nmodified": 0})> Db.persons.find (){"_id": 2,

The role of the primary key: 1) To ensure the integrity of the entity; 2) speed up the operation of the database 3) when you add a new record to a table, the database automatically checks the primary key value of the new record and does not allow

First, get Insert record primary key valueUse Statement.return_generated_keys to identify where the statement was created, and then get the Getgeneratedkeys methodPreparedstatement=conn.preparestatement

How do I set the shortcut key for Sublime text to preview the HTML file in the browser ?, STEP 1   Tools> Build System> New Build System STEP 2 & Lt; img src = "https://pic3.zhimg.com/37243c718bd49b496f83ed8e61a4f876_ B .jpg" data-rawwidth = "798"

Check the settings for SSH keys$ CD ~/.ssh/If "No such file or directory" is displayed, skip to step three, otherwise continue.Back up and remove the original SSH key settingsIf a key file already exists, you need to back up the data and delete it$

What is the shortcut key for ZendStudio to wrap in the tab? For example, how do you enter , Zend Studio will automatically completeIf you press enter, there will be no line breaks, and the cursor will only Skip laterIf you want Insert a blank

We have introduced the ssh remote logon protocol for linux and the ssh password-less logon method. Here, we log on to linux using secureCRT and putty in windows to see how to create, configure, and log on to linux, make a memorandum. 1. Create a key

@ Warning: remote host identification has changed! @ It is possible that someone is doing something nasty! Someone cocould be eavesdropping on you right now (man-in-the-middle attack )! It is also possible that the RSA host key has just been

Professional Edition: W269N-WFGWX-YVC9B-4J6C9-T83GXEnterprise Edition: Nppr9-fwdcx-d2c8j-h872k-2yt43Home version: tx9xd-98n7v-6wmq6-bx7fg-h8q99Education version: NW6C2-QMPVW-D7KKK-3GKT6-VCFB2Professional Edition

How do I set the shortcut key for switching the Input Method in win10? When we use the newly installed win10 system, we will find that the commonly used ctrl + shift key cannot be used to switch the input method. How can we set back the familiar

Today I wrote a gpio as an example of input port on the basis of LED light. In the experiment, I use a key as IO input device, then use Bb_black to collect the current information.First Step: Hardware introduction1, Key introductionTouch the

First: check if SSH exists (Ls-al ~/.ssh)$ ls-al ~/.sshLists the files in your. SSH directory, if they existSecond: Generate a new SSH key (ssh-keygen-t rsa-c "[email protected]")$ ssh-keygen-t rsa-c "[email protected]"creates a new SSH key, using

These keys are primarily used for volume activation of new systems and are useful for enterprise organizations with multiple devices. The key versions are as follows:Windows 10 Pro: W269N-WFGWX-YVC9B-4J6C9-T83GXWindows 10 Professional Edition

If we get used to the OOP, we know this it often mentioned the concept about "reusable", actually that bring different lay ERs of meanings about software design, one could is, if it's reusable, then we'll be able to use it in new software with Less

　　In the workflow form, the drop-down box control will appear as follows because of the Ueditor editor650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M02/5C/91/wKioL1Ud6qGDBKfOAABugp1yl0M481.jpg "title=" Select0 (04-03-09-13-46). png "alt="

These days have been concentrated on the development of iOS, just to record the problems encountered. The problem this time is that if the user name and password are encrypted on the iOS client based on the public key that is obtained.The public key

Public key *. rpm is not installed solution> [root @ RedHat mnt] # cd/opt/cdrom/Packages/[root @ RedHat Packages] # yum install google-chrome-stable_current_i386.rpm Loaded plugins: refresh-packagekit, rhnplugin This system is not registered with

Disable the return key for android detailsIn today's project, you need to use the return key in your own actionBar. The method used is the method of My Father activity recorded last time. Android. support. PARENT_ACTIVITY For more information, see:

Key for customizing HashMap and customizing HashMap If you use a custom type as the key of HashMap, you must reload hashCode () and equals () at the same time to find the custom key in HashMap. For example, the custom Point class: public class Point

1. Traversal of the Map collectionMap--Couples onIdeas:A: Bring all the husbands together.B: Walk through the collection of husbands, get every husband.C: Ask the husband to find his wife.Transformation:A: Get all the keysB: The collection of