java database interview questions

TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily change the implementation later.(4) Always use type-safe generics to avoid classcastexception at run time.(5) Using the immutable classes provided by the JDK as key to t

choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily change the implementation later.(4) Always use type-safe gener

type as needed. For example, if you specify a size, we will choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily ch

This content is excerpted from the Java Web Lightweight Development Interview tutorialFor qualified programmers, basic database operation skills are required, which are embodied in the following three areas.L First, for a class of databases (such as MySQL, Oracle, SQL Server, etc.), will be basic additions and deletions to the operation, will use some basic funct

corresponding action, while the user's data to fill the corresponding actionform, and then the Actionform is distributed to action for processing.3.Action automatically calls the Excute method, in which the action takes the user-filled data from the Actionform and invokes the model (JavaBean) for processing, and then displays the results of the processing in a different view (JSP page)struts-config.xml:struts 's configuration file .It says that each user's request is handled and forwarded throu

: This article mainly introduces interview questions: I will talk about how to optimize MYSQL database queries. if you are interested in PHP tutorials, please refer to it. 1. Optimize Data types There are multiple data types in MySQL. if you are a DBA, you are strictly checking the data type according to the optimization principle. However, developers may choose

StudentLeft JOIN choice_info choice on choice.student_no = student. ' No 'GROUP byStudent. ' No ') AWHEREA.count > 2;4. Check the names of all students with test scores, name of course and exam results, and place the results in a new permanent table (assuming the new table is named Tb_rel_new)Note: This topic contains new tables and insert query data Inquire SELECTA. ' Name ' Studentname,Course. ' Name ' Coursename,A.gradeFromCourse_info CourseLeft JOIN (SELECTStudent. '

cannot implement a function other than the ' = ' Logic of the case search function. Case function Matching principle The case function differs from switch in that the case only returns the result of the first match, and Switch will continue the subsequent judgment without interruption, and all matching results will be executed. Case search function is more flexible than simple case function The flexibility of the case search funct

I used to have only one Java interview question topic. Now I have divided into the following topics: Java interview questions are of course the focus, all of which are Java programming and directly related to the design. Intelli

COSCO Java interview question zzz COSCO Java interview questions Java training materialsI. Java language1. Three basic features of object-oriented2. Concepts and differences between met

. Briefly describe the meaning of the viewThe meaning of a view lies in two ways:1) simplify complex queries. If you need to perform a complex query frequently, you can build a view based on this complex query, and then query this view.2) Restrict data access. A view is essentially a SELECT statement, so when you access the view, you can only access the columns that are involved in the corresponding SELECT statement, and the other columns in the Base table act as security and secrecy.11. What ar

Transferred from: http://icyfenix.iteye.com/blog/715301The background of this post is tonight to see JE on this posting: http://www.iteye.com/topic/715256, the words written on impulse, if you can, can have other interviewers to analyze their interview questions asked, it may be a very meaningful thing. In the company as a technical interviewer for a few years, from graduating students to work more than 10

Java and C common technical interview questions 2015 (Continuous updates ...), 2015 updating 1. Differences between overwrite and overload Overload is an Overload. It uses the same name as an existing member to declare attributes or methods, but the parameter list is different from that of the original member. Override is mainly used for method rewriting between

dispatch and dispatch, and a smaller unit that can run independently than a process. Thread's StrokeThe sub-scale is less than the process, which makes the multi-threaded procedure highly concurrency, and the process typically has independent memory units at execution time, while the threads can share memory. Programming with multithreading often leads to better performance and user experience,But multithreaded programs are unfriendly to other programs because they may consume more CPU resource

Java interview questions Basic knowledge:1. simple principles and applications of the Exception Handling Mechanism in C ++ or Java. When a Java program violates the Java Semantic Rules, the Ja