has such a logic, a piece of data, if there is in the database, then update, if it does not exist, then insert. But now there are ten thousand. So how to accomplish the task efficiently? ...
take MySQL as an example, what is the difference (principle and efficiency) between in and exists and between not in and not exists? What about using indexes? Say that not in and < > will not use indexes, won t you? ...
The index is a data structure in which the leaf node of the b + tree holds pointers to the actual rows. what about clustered indexes? what does InnoDB s clustered index mean by storing B+Tree indexes and data rows in the same structure? Does mean that...
EXPLAIN SELECT s.id, s.name, s.price, s.unit, s.qty, s.remark, s.image, s.cuft, s.volume, s.status, s.vender_id AS venderId, s.booth_id AS boothId, s.booth_no AS boothNo, s.show_booth_no AS showBoothNo, s.name_en AS nameEn, ...
such as the title. see that MySQL generates a tree for the primary key, and the leaf node holds the row data corresponding to the primary key. The secondary index leaf node holds the value of the primary key. excuse me: does the leaf node of th...
how can I get the state of vuex in vue-router? router.beforeEach I want to make login judgment in this. How can I get the user information in state? ...
I didn t want to register repeatedly, but wanted to integrate into a microservice, so I began to search, think, and design, but I encountered a key problem as I walked: where should I put my user data? the reason for this confusion is to consider t...
use iview-admin, in which the data are all randomly generated by mock. I defined an interface, wanted to cancel mock, and changed the content of config index.js devdev this is an error reported when visiting a web page how can I use the iview-adm...
1. Currently, crontab, which comes with centos, automatically executes scripts. But there will be some errors in time. the logic now is: the php code automatically queries the work order to compare the first 10 minutes of the current time with the appoi...
the front page is as follows <div class="form-group"> {!! Form::label( phone , ,[ class => col-md-2 control-label ]) !!} <div class="col-md-5"> {!! Form::text( phone ,null,[ class =>...