when you look at the data structure recently, there is a question: why should each element of the array have the same data type?
when you look at the data structure recently, there is a question: why should each element of the array have the same data type?
personal opinion: in order to improve the efficiency of storage and reading, if the array allows various types of data, then each element stored will be boxed, and each element read will be unboxed. The steps of boxing and unpacking can be omitted by unifying the data type.
since stipulates , why? This is the same as specifying to take 3.14 , and you have to ask why you can't take 3.1415 . Why is this necessary?
the title itself is incorrect, and different programming languages have different implementations. For example, in js syntax, any type of data can be stored in an array.
for example, the isolation level of transaction An is repeatable read my understanding is that a read sql statement of transaction An is the same as the result repeated many times, regardless of whether or not other transactions have changed the data ...
F12 sees that ajax has so many request parameters that I can t use most of them. Can I remove such parameters? Don t so many parameters take up bandwidth? ...
in sql server database, an insert trigger is set for a table, and a new view is created in the trigger. How to design and write statements? Thank you ...
there are 200000 data in the data, and each data has a typical list of words of 5000 length [{aVl1}, {bju 2},.], and typical dictionaries of 5000 length {{aRom 1}, {bjr 2},.}, use pyMongo to find100 data, the traversal of cursor is particularly slow, is...
now there is a scenario in which you subscribe to kafka s topic, to get the message in real time, then check the database through the message content to get some fields necessary to build the document, and then consume the constructed document. now a...
learn to forget one at a time. Is there anything you can do to play with? to master it thoroughly ...
as shown in the figure below, does SQLAlchemy have a simple way to directly declare that the specified field is not mapped serialized? for example, does java s Hibernate framework have such a function? (although there are other "indirect " solut...
as shown in the figure, a simple add and query operation takes up to 1 second [environment: windows + python3 + django2]. (the amount of data in PS: is not much, and todo_list has only 2 rows of data, which is still so slow.) def get(request): -...
there is a set collection of tag classes in the user class; maintain relationships only from the user class, one-to-many @ OneToMany @JoinTable(name="shuo_tag", inverseJoinColumns=@JoinColumn(name="tag_id"), jo...
https: github.com thymeleaf . I use jpa, to cascade the two classes through annotations. in the html page, when you get the object of any class through the thymeleaf tag, it will appear . java.lang.StackOverflowError: null at sun.reflect.misc.Refl...
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designing a complete project includes not only the front-end project design, but also the need to build local servers and databases. As a front-end developer, what kind of database should you choose? There are a lot of people around who are using mongodb...
one class @Entity public class Shuo{ @Id @GeneratedValue private int id; private String title; private Date date; String content; @ManyToOne(cascade = CascadeType.REFRESH) @JoinColumn(name = "user_id") private User user; : @OneT...
there is no error in compilation after being written using the following method, but the execution result has always been: 2pint 2pint 2pens 1966080, solve! LNode s (LNode head1,int n) {int iLecture s; LNode p, s, head2; head2= (LNode ) malloc (...
Front end code <li class="block">: <img :src="productImg" alt="real-photo" v-if="productImg"> <input type="file" ref="proupload" name="file"...
how do you design database fields like youtube pages that show whether you have pressed like or dislike? And go to the database to judge when the user arrives at the page? whether the design idea is like this Post table id picroute likeusers dislik...
2018-04-10T08:26:03.830775Z 0 [Note] usr sbin mysqld (mysqld 5.7.20) starting as process 9836 ... 2018-04-10T08:26:03.923709Z 0 [Note] InnoDB: PUNCH HOLE support available 2018-04-10T08:26:03.923741Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic b...
this is a question post with nothing to do, the problem encountered by the beginner of programming, there is no solution, I do not know which seniors have ideas, but also hope to give me some advice. is like this The project uses spring-data-jpa as ...
tooltip: { pointFormatter: function () { console.log(this) let startTime = dateFormat(this.x); let endTime = dateFormat(this.x2) if (this.r)...
Table T_USER T_ROLE : the following is the table creation and data script drop table if exists T_USER; CREATE TABLE T_USER( USER_ID INT, USER_NAME VARCHAR(25) ); INSERT INTO T_USER VALUES(1, USER_A ); INSERT INTO T_USER VALUES(2, USER_B )...