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db.dept.distinct("dname") Sort//按dname降序排列 db.dept.find().sort({"dname":-1}) //按dname升序排列 db.dept.find().sort({"dname":1}) Page out//获取前5条记录 db.dept.find().limit(5) //跳过5条再取5条(取6-10) db.dept.find().skip(5).limit(5) Indexdb.dept.ensureIndex({"dname":1}) db.dept.dropIndexes() db.dept.find({"dname":"java99999"}).explain("executionStats") Java access MongoDB based on Mongo-java package basic accessAPI Introduction - Mongo

Label:Summary of MySQL Basics primer about the database: database is a software developer to master the basic tools, the process of software operation is the process of manipulating data, the data in the database is nothing more than a few operations: increase-delete-check-change. after the MySQL installation is complete, you need to configure the variable environment, locate the configuration path, and then import the MySQL installation directo

Zepto basic knowledge (3), zepto basic knowledge 41.HeightHeight () type: numberHeight (value) type: selfHeight (function (index, oldHeight) {...}) type: selfObtains the height of the first element in the object set, or sets the height of all elements in the object set.$ ('# Foo'). height () // 123$ (Window). height () /// 838 (viewport height)$ (Document). height () // 22302 42.HideHide () type: selfYou c

Public platform development and learning series (III): webpage authorization for obtaining basic user information and basic public information Official documents: http://mp.weixin.qq.com/wiki/4/9ac2e7b1f1d22e9e57260f6553822520.html In the interface permission table Change it to the domain name of the server According to the official documentation, an authorization Page Link is required, which can be i

Canvas basic learning (3): canvas basic learning I. image loading controls Multiple images are often used in canvas effect creation. To improve the user experience, you need to provide users with excessive page effects during image loading. I used Sonic. js in the project, and its address on git is. Is: The call code is also relatively simple. The following is a self-written image loading Tool (Function (

Basic string operations and basic string operations # Define _ CRT_SECURE_NO_WARNINGS # include

Basic Binding knowledge (organization) and basic binding knowledge The essence of a program is the data addition algorithm, Algorithm distribution a. Database B. Read and Write back data c. business logic d. Data presentation e. Interface and logic Interaction AB is stable. c is closely related to customer requirements (Development core). d. e is responsible for UI and logic interaction. WPF makes the prese

Introduction to basic knowledge of ASP. NET master pages and basic knowledge of asp.net What is a template page? Using the template page, you can easily and quickly create a unified style ASP. NET Website, and it is easy to manage and maintain, improving efficiency.The template page defines the appearance and standards required by the web page. Each content page containing the displayed content is created o

Basic knowledge of LAMP configuration course, basic knowledge of lamp After a day's course, I am still very interested in it. [Root @ localhost ~] # Root User Name Localhost local ~ Different users in the Home Directory # The current user is an administrator $ the current user is a common user Command Format: Command Option parameters (options and parameters are interchangeable) Pwd is the current directory

Example of alert pop-up prompt box in the basic JavaScript tutorial, basic tutorial alert A prompt box is displayed for the alert command. This section provides several simple examples for beginners to learn JavaScript. The following code is an example of a pop-up prompt box: Copy codeThe Code is as follows: Save the above Code as alert.html (or alert.htm) in a text editor (such as a WordPad or other advanc

Basic Structure of Win32 application, basic structure of win320 Introduction Win32 API is an application programming interface used to create Windows applications. Generally, a Win32 application contains the following parts: 1) application portal; 2) Registration window class; 3) create a window; 4) display window; 5) Update window 6) message loop; 7) send messages;1 application portal The Win32 application

Java basic set classic Training Questions, java basic set classic Question 1: 10 random strings are required, each string is not repeated, and the characters (a-zA-Z0-9) in each string are also different, each string is 10; Analysis: * 1. When you see this question, you may think of many methods in your mind, such as determining whether the generated string contains duplicates, and determining whether the l

Basic JDBC learning and basic jdbc 1. Concept: java Database Connection Technology 2. JDBC:Is a specification that provides Interfaces(Interface-Oriented Programming) 3. jdbc api:Provides interfaces and classes called by programmers, Integrated in the java. SQL and javax. SQL packages. For example:DriverManager class (managing different JDBC drivers), Connerction interface, Statement interface, and ResultSe

Exception in notes of python basic tutorial, and python basic tutorial Errors in your own way When a raise statement is used to raise an Exception, you can use a class (which should be a subclass of Exception) or an instance parameter as the raise object. When a class is used, the program automatically creates an instance, as shown in figure >>> Raise Exception ('hyperdrive overload ') Traceback (most re

Python _ basic syntax _ 01, python basic syntax _ 01 There are still a few months before graduation. I wanted to go to the company for an internship early, but I don't want to release the gb School. Well, in this case, learn the language. Reference and http://www.cnblogs.com/vamei, I followed this blog tutorial, specific you can view the blog of this blogger. Remember to stick the code and comments of the s

Java basic interview (1) and java basic interview 1. When I use the final keyword to modify a variable, can the reference not be changed, or can the referenced variable not be changed? When you use the final keyword to modify a variable, it is suggested that the variable cannot be changed, and the content in the object to which the referenced variable points can still be changed. For example, for the follow

Python basic training Question 2-tuples, dictionaries, and python Basic Training 1. determine the value in the tuples >>> a = ( 1, 2, 3, 4, 10 )>>> 10 in aTrue>>> '10' in a False 2. Modify the values in the tuples. Because the tuples cannot be directly modified, You can first convert them into a list. After the list is modified, assign them to a new tuple object. >>> a = ( 10, 20, 30, 40 )>>> l = list( a )>

Basic Java syntax (1) ---- keywords Identifiers (Java language identifiers naming rules Java language package name, class name, Interface Name, variable name, function name, constant name naming rules), java basic syntax I. Keywords Keyword definition and features Definition: a special character string (Word) that is used for special purposes ). Feature: All letters in the keyword are in lower case. Some

Basic data type, java Basic Data Type Byte tt = (byte) 130 is equal to-126. Byte occupies one byte, 8 bits. The first digit is the symbol bit. 0 indicates a positive number, and 1 indicates a negative number. Therefore, the value range of byte is [-128,127]. The binary value of 130 is 00000000000000000000000010000010, Which is truncated to byte type. Only the last 8 digits are retained, that is, 10000010. t

Basic knowledge of MySQL storage engine and basic knowledge of mysql Engine We mentioned MySQL transactions in previous articles. Now everyone should know about MySQL transactions. Do you still remember the ACID principles of transactions? If you do not remember, you can review MySQL's first knowledge of transactions. In fact, if you are more rigorous, it should be the MySQL InnoDB Storage engine, because i