Tag：Quotation marks
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The role of ` in SQL statements
The role of ` in SQL statements Make the attack and defense World Web ZonesupersqliTopic: when building SQL statements, you can parse if there is a ‘in the SQL statement, but not if there is no’. According to the information, it is usually used to explain that the contents are database name, table name and […]
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Zsh Development Guide (Part 20 code style)
Reading guide Because the shell script syntax is relatively flexible, and the programming languages familiar to the developers who write shell scripts are also quite different, it is easy for everyone to write code with different styles. It’s ok if you only use it by yourself. If you cooperate to develop the same project, different […]
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Mongo change data type
Mongo writes in quotation marks, resulting in some numeric fields of string type. Modify the field type to numeric type. db.Report99.find().forEach( function(doc){ db.Report99.update({‘_id’: doc._id},{$set:{“begin-quantity”: parseFloat(doc[“begin-quantity”])}}); // Change to floating point number db.Report99.update({‘_id’: doc._id},{$set:{“end-quantity”: NumberInt(doc[“end-quantity”])}}); // Change to integer } ); Mongo4.2 + version, the parameters can be as follows: db.getCollection(“my-report”).update( { “begin-quantity”: { $type: “string” […]
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Python learns a series of print () functions and variables
IPrint() functionThe main function of the print() function is to print the contentThe print() function is used in the following ways:Without quotation marks >>> print(520) 520 >>> With single quotation marks >>> print(‘Hello word!!!’) Hello word!!! >>> With double quotes >>> print(“Hello word!!!”) Hello word!!! >>> With three quotation marks >>>Print (” ‘I’d like to […]
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The solution to the program (because of the problem of numbers) does not respond
Problems encountered I spent half an hour writing a code yesterday, but I didn’t expect that onlyinputStatement. The following is a part of the code: import random After running,ifThe following statements are completely invalid. Solving process First, I checked all the statements below and found no problems, and python did not report errors.After that, I […]
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The difference of three kinds of quotation marks in shell
There are single quotation marks, double quotation marks and back quotation marks in the shell. The usage of each quotation mark is also different. Let’s sort out the use of quotation marks in the shell Single quotation mark str=’this is a string’ Characteristics of single quotation string: Any character in the single quotation mark will […]
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Zero basic introduction Python tutorial section 4 and basic syntax
In order to make my tutorial friendly to novices, I use the case interpretation method, that is, first give a piece of code, and then lead to the concepts and methods that need to be mastered. The concepts that need to be mastered in this section include the following points, but please don’t study these […]
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Easily customize debugging with debuggerdisplay in. Net
preface There are many ways to debug, but in today’s monitoring window we will see the monitoring of variables. Of course, here we customize the internal variable value, or the content of variable display and calculation. Note: the monitor window can display multiple variables at one time during debugging“ The Quick Monitor dialog box displays […]
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Linux shell variables
Defining variables #There can be no spaces around the equal sign url=http://www.qq.com/shell/ Name =’My website ‘ author=”wu” Using variables #Curly brackets are recommended for all variables {} echo $author echo ${author} echo “I am good at ${skill}Script” #It is recommended to use quotation marks to avoid format confusion LSL=`ls -l` echo “${LSL}” Modify the value […]
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[Python] – 2-string Foundation
introduction This article introduces the basic operation of string in Python, including three kinds of string expression, string connection, the use of escape character, and the use of placeholder. Contents of articles 0 × 1. How to output string0 × 2. How to use escape character0 × 3. How to connect strings0 × 4. How […]
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Elisp 10: macro
Last chapter:library In the previous chapter, we implemented the library newbie.el, which only defines one function. In fact, this function can be defined as a macro instead of a function, and it can make the calling code more efficient. Because calling a function is like taking a bus to a station, while calling a macro […]