at present, if you encounter such a problem of using mysql, first describe the scenario (some simplifications have been made to facilitate the answer): now there are two machines that use the same database account and access and operate a mysql addres...
scenario: when the business level deletes (physically deletes) a piece of data from Table A, the data is inserted into Table B. set up a trigger on table A CREATE OR REPLACE TRIGGER cmsinfo AFTER delete ON tablea for each row BEGIN IF DELETING THEN ...
about the design of the fields of a table a during the design phase of the data table during the development of the project, including the creation time and status of the id,name,. first of all, according to my business needs, I need to group the data ...
suppose a web site has a backend, and the default is test.com admim (test.com is my own personal domain and must be encrypted to log in, so the test will have a test manager account, and there will be an official manager account), and you can add back-...
there is a need to submit a db file for sqlite, but every time sqlite loads are turned off, the db file is modified even if no modification is made. As a result, it is impossible to use md5 for file deduplication directly, so is it a bit slow to use sql ...
echo "<td> <a href="{$row[ Link ]}">{$row[ Name ]}< a> < td>" ;...
Shopping system, how to make the sub-table in the commodity evaluation table? on the one hand, users need to check the reviews they have written, and on the other hand, merchants also need to check the reviews of their products. it will be troubl...
problem description I want to update the mongodb database and store an array with some deleted elements in mongodb, but when at least two threads perform this task at the same time, there is a second kind of update loss problem, such as the original a...
1. Connect to a Mysql database locally but need to use a table data from a remote Oracle database. How can you achieve this function? (you cannot directly copy the table, because the table data in oracle is real-time changing Mysql also needs the latest...
problem description has a relationship to manage: has multiple app, multiple tags per app, tag, multiple user per tag. User may be under tag11 or tag12 of app1, or under tag21 or tag22 of app2. how to establish a relational table in this case? add...
I want to make a data length limit, for example, if the length of a collection in a database exceeds 1000, sort by time, delete the old data, and then add new data. now is the length limit and sorting I am more clear, but after sorting why remove did no...
I am currently working on the design of a database table for a data management system, but I have encountered such a situation: for example, there are two types of data, one is grouping group, the other is member member; , and then each group has a lo...
topic description at present, there is a product that the user places an order to reduce inventory, the order is cancelled to increase inventory, and the backend modifies the inventory quantity. There are three different ways to do this. How about S...
assume that the original data id type time 1 1 201X-XX-XX XX:XX 21 201X-XX-XX XX:XX 3 1 201X-XX-XX XX:XX 4 2 201X-XX-XX XX:XX 52 201X-XX-XX XX:XX query statement Select t.typepart. TimeMAX (t.id), t.* FROM t WHERE t.time between 2018-08-01 ...
RT A user belongs to a group, each group has multiple users, and each group has a group leader user (table) userid groupid . group (table) groupid ownerid . such a design from the ER diagram, each of the two tables has a 1-to-N connection to...
could you tell me how to query the sql statement and how to implement it on ef? thank you ...
or answer my question directly: when a sql of select has a primary key and an index, what is the order of its execution? is there a big god to find it first from the primary key or from the index? ...
when designing an attachment storage table for a system, do you use decentralized storage of information to each required table? Or do you centrally store the attachment information in a table and then associate it in the table you need to use? Or are t...
Local plans to write a large amount of data to another database. A tag field is returned for each piece of data written successfully. This field needs to be updated to the local corresponding data, using whether php, can use php script to run ....
how does neo4j perform script batch import and query under Windows cypher-shell? ...