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The first chapter: 1. What's in Java?The JDK (Java Development Kit) includesJre (Java Runtime Environment)---------->JVM (Java Virtual machine)Application (JAVAC)Java API and some common jar packages; Java benefits: A. Object-oriented; cross-platform/portability for B.java; Java execution Process: Java source file-------> Compiler-------->.class file--------->JVM explained. Chapter II:Variable:Use a single letter or character to express words. The first thought of char;String n

value of a column MIN () returns the minimum value of a column SUM () returns the value of a column To ask for an average of a column Copy Code code as follows: Select AVG (prod_price) as Avg_pricefrom products; -Count Count the number of rows in a table using count (*) (whether null or not) Use Count (column) to count rows with values for a particular column, ignoring null Sum Use SUM () to return the value of the specified column The above is a smal

transaction, rolls back uncommitted transactions, forces all users to connect, and performs checkpoints to write dirty data to the data file. However, the speed of the shutdown can also be affected by the number of transactions and user connections⑶shutdown Transactional: When the database is closed, the current connection continues, but the new connection is not allowed, and the database is closed once all the current transactions have completed⑷shutdown Abort: Unsafe shutdown mode, which disc

; ID NAME ID Age--------------------------------------------------1 AAA 1 20 3 30 from the above display you can see that the left outer join is based on the table on the left. Generally speaking, the left table is all displayed, and then the right table ID and the left table ID of the same record is "stitching" up, such as the record ID 1. If there is no matching ID, such as T1 in the ID 2 in the T2. There is a null display. Right outer join process just the opposite。

function keyword functionsA recursive function that contains statements that call itself directly or indirectlyInclude,require loading a function library file into a script programUse special pointers in the $this classAccess or operation in class, $thisconst Keyword Class constantsConstruction Method _construct ()destructor Method _destruct ()Static classThe "::" symbol is called a range resolution operation that can be used to access static members, static methods, and constants, and can also

HTML5 First chapter (Introduction) 1HTML5 First chapter (Introduction) 2HTML5 First chapter (Introduction) 3HTML5 First chapter (Introduction) 4HTML5 First chapter (Introduction) 5HTML5 First chapter (Introduction) 6HTML5 First chapter (Introduction) 7HTML5 First chapter (Introduction) 8HTML5 chapter II (Tools and materials) 1HTML5 chapter II (Tools and materials) 2HTML5 Chapter III (tags, page structure and ... (1)HTML5 Chapter III (tags, page structure and ... (2)HTML5 Chapter III (tags, page

browsers. Most implementations now follow the ECMAScript defined in ECMA-262 Third edition. The following is a brief summary of the basic elements in ECMAScript:The basic data types in ①:ecmascript include Undefined,null,boolean,number and string;②:ecmascript does not define separate data types for integer and floating-point values, and the number type can be used to represent all values;③:ecmascript also has a complex data type, the type of object, which is the underlying type of all objects i

used to px (pixels), EM,% percent, you should pay attention to the fact that these three units are relative units.1, PixelWhy are pixels relative units? Because pixels refer to dots on the display (the CSS specification assumes "90 pixels = 1 inches"). The reality is that the browser uses the actual pixel value of the display, and most designers now tend to use pixels (px) as units.2, EMis the font-size value of the given font for this element, 1em = 14px If the element's font-size is 14px, and

notation: if (222) {} Else if (111) {} Else if3. Small Knowledge Points:I is often used in the ①for cycle, the variable named I is a traditional practice: I means "increment" (increment)② can use ternary arithmetic to replace If-else, which makes the code brief, but the logical relationship is not obvious. With which, to see you in the mood③onclick event support for keyboard access has been good (PS: In all browsers, the TAB key is moved to a link,

next step is to build and connect the library to build on conditions. In the top level CMakeLists.txt file we add the following:# Add the Mathfunctions library?#if (Use_mymath)Include_directories ("${project_source_dir}/mathfunctions")Add_subdirectory (mathfunctions)Set (Extra_libs ${extra_libs} mathfunctions)endif (Use_mymath)# Add the ExecutableAdd_executable (Tutorial tutorial.cxx)Target_link_libraries (Tutorial ${extra_libs})The use of the Use_mymath setting determines whether the mathfunct

the software;6. Use of the Software/service environment (in the Office/home/sofa/bed/bus/subway ...);7. Living/working conditions;8. Knowledge levels and competencies (degree of education, familiarity with computers and the Internet);9. Motivation, purpose and difficulty of the user (difficulty = problem to be solved);10. User Preferences.Function-driven Design: 1. Construction of the overall model (Develop an Overall models);2. Construct a list of functions (build a Feature list);3. Developmen

It is not enough to look at the user's surface language and actions, so we need to find the motivation behind the user. Otherwise the implementation of the function is always unable to obtain the user's satisfaction. So that the product may have to be "reworked" several times. "Rework" not only tests the software development team, but also tests the user's patience. Perhaps the user feels that the software purchased in your company is so troublesome that next time he will consider chan

process group knowledge points to explain the project.A), project five process group the second planning Process group describes and introduces the following knowledge points:1 ), the project planning process in the overall management of the project: preparation of the project management plan2 ), project scope Management in the field of planning: scope management plan, scope definition, establishment WBS3 ), time management: Activity definition, activity sequencing, activity resource estimation

new hard drives2 Enable LVM and create a VO logical volume and format the EXT4 formatPvcreate/dev/sdb1Vgcreate ZHAO/DEV/SDB1//Join a groupView: VgdisplayLvcreate-n vo-l Notoginseng Zhao//37 PEMkfs.ext4/dev/zhao/voMkdir/zhaoMount/dev/zhao/vo/zhaoDf-hExpansion VO Logical Volume Capacity:Umount/zhaoLvextend-l 290M/DEV/ZHAO/VOE2fsck-f/DEV/ZHAO/VO//Check disk full typeResize2fs/dev/zhao/voMount/dev/zhao/vo/zhaoDf-hRESIZE2FS/DEV/ZHAO/VO 120M//reduced to 120MLvreduce-l 120M/DEV/ZHAO/VOLogical Volume S

between regression testing and unit testing?Chapter IIIThis chapter is mainly from the measurement and development of personal ability and the professional development of software engineering, the understanding of general software design thought and the engineering idea, the promotion of professional skills and the actual results achieved. Become a software engineer, first of all to learn and accumulate software development-related knowledge, continuous learning, and constantly accumulate, impr

integrated into the framework of automated tests.8. Unit test must be saved and maintained together with the product codeChapter three Development Road of specialized software engineer1. Certificate of Examination. Computer grade examination and the national computer Technology and software professional technical qualification examination.2, the accumulation of software development-related knowledge, improve technical skills.3. Accumulate knowledge and experience in problem areas.4, the general

development trend?After reading the second chapter know that the software is required unit testing, before this is not a concept, and unit testing to be synchronized with the software update, unit testing to cover all code paths, unit testing can be done by your software can not do things in the "unit" in the expression. If there is no unit test, sometimes some of the hidden dangers themselves do not know, until the later discovery and modification is very complex. In the case of a unit test, l

: Memory in the kernel is not paged, each byte is used, and the physical memory is reduced by one.4. It is difficult to perform floating-point arithmetic when kernel programmingThe process of user space is a floating-point operation, the kernel completes the conversion of integer-to-floating-point operation mode, but the kernel itself cannot be trapped.5, the kernel to each process only a small fixed-length stackThe stack of user space is large and can grow dynamically.The kernel stack has an ex

to providing a log output function similar to the PRINTK function, he also allows developers to link target devices directly on the PC via GDB. The kgdb contains two parts, the KGDB kernel and a set of connection interfaces. Although it is easy to write messages to the log file or console using the PRINTK function. However, the heavy use of the PRINTK function to frequently manipulate log files or console device files (/dev/console) can severely affect Linux drive performance (so that the speed

example:The initialization function crashes, and the behavior is that the current Linux driver module is not used by any other Linux driver, but the display has been referenced once. The workaround is to clear 0 of the current Linux driver Module reference counter. The last time I did this experiment in Mr. Jing's experiment class, I encountered this problem, the Development Board has been issued a sound can not be closed, only by restarting the Development Board to avoid, but always restart th