The index of numeric type is b-tree tree, but what about string type? Is it possible to map a numeric value to each string and arrange it according to the b-tree tree? ...
is a project for a school. The system is windows server 2012 R2. The running environment IIS8.0, sets up two websites on iis, using different ports. One website handles php requests and the other deals with static resources. Will it improve the response ...
The project gives the account password of the database. At present, you can only connect through the ssh proxy using navicat. I think the connection can also be achieved through the command line. ...
select I. I. ID. I. Price. I. Amount. Name from orderitem i, goods g where order_id =? And i.goods_id = g.id java.sql.SQLException: Cannot create com.yanzi.model.OrderItem: com.yanzi.model.OrderItem Query: select I.id from orderitem i, goods g where or...
< H2 > complete error: < H2 > SQLSTATE[HY000] [2054] The server requested authentication method unknown to the client < H2 > docker-compose.xml < H2 > mysql: image: mysql:8.0 volumes: - . mysql data: var lib mysql - . mysql my.cnf...
I have created several database, in the mysql database, such as db1 and db2, to check the usage of mysqlbinlog. It seems that the scope of action is for the whole database, that is, the logs of db1 and db2 are stored together. is there a way to do inc...
what I do when I generate an order is: while ($row = mysqli....) { $id = substr(date( YmdHi , time()), -10); } because there will be dozens of orders in one second , but this will lead to the same order number . I have thought about using "uniqid "...
mysql ...
uses the thinkphp framework for authority authentication based on auth. currently there are four tables in mysql: 1, user (user table) 2, auth_group (user group table, such as administrator group, employee group) 3, auth_group_access (previous assoc...
ladies and gentlemen, created_time stores string types in my database. How to query the amount of data per hour during the day? how to write this sql? ...
there are two tables, one document table and one case table document (id,case_num,document_name) case (id,case_num,case_name,status) the case_num of the document table corresponds to the case_num of multiple case tables the case_num format of the ...
recently, app is going to do a feature similar to giving likes by Qzone. When you go to the database, you can use the new data type json after mysql 5.7 to store the like user id, so that every time a user gives a like, you can use json_merge to add an ...
each commodity is limited to 1000 copies per day, and the robbery starts at 10:00. Select count from table where date = year, month, day, for update lock. How many copies have been sold on the same day? If it is not more than 1000, continue with the fol...
I have seen a lot of articles on mysql indexes that say that if a field has a small range of values (a large number of duplicate values), there is no need to establish an index. but my actual test: user_type_id field has an index: then executi...
first of all, the system uses the manjaro (linux) system. I installed mySQL, in the project directory, but when I node timetrack_server.js the file, I made the following error: home dema codeSpace studyNode testMySQL timetrack_server.js:49 if ...
Why did it start at 11? An extra 1. has been added. CREATE TABLE mytest13 ( id INT PRIMARY KEY AUTO_INCREMENT, age VARCHAR (10) ) AUTO_INCREMENT=9; SET auto_increment_increment=10; INSERT INTO mytest13 (age) VALUES ( 20 ); INSERT INTO mytest13 ...
the demo, database table on the reference network has been created automatically, but the following database errors were reported when the project started. Please ask the gods to give us some suggestions. Thank you . SQL: INSERT INTO ACT_GE_BYTEARRAY (...
this is the definition of the index in the MySQL table recommendation in Alibaba s Java development manual, where: the primary key index is named pk_ field name isn t an index created for the primary key by default? how do you name this index? ask B...
how does innodb assist store duplicate column values Is stored with extra pages like this? ask the boss to answer . ...
problem description 1. A certain field of a table has a high degree of repetition, so how much repetition is it not suitable for indexing? 2. If a table does not build an index other than the primary key, how old will the table be, such as a slow que...
$date = strtotime(date("Y-m-d")); $day = date( d , $date); $month = str_pad($_GET[ m ],2, 0 ,STR_PAD_LEFT); $year = date( Y , $date); $firstDay = mktime(0,0,0,$month, 1, $year); $title = strftime...
sometimes you need to deal with strings, but invisible characters are not visible, which is troublesome. Can display invisible characters? ...
what to do when the address selected on DiDi s home page of app can be pushed to the top? ...
if there is a set of operations to be performed within a method that belongs to the same transaction, how is the transaction in progress handled when tomcat closes? Will tomcat wait for the transaction to finish? Or does the transaction become incomplete...
when you start to learn Android, when you finish your homework, you find that the notification you wrote will not appear on the virtual machine on time if you customize an instance, but if you change the time to System.currentTimeMillis (), you will be ...