Found a total of 10000 related content
Creating and Managing Database Views in MySQL
Article Introduction：The database view is a virtual table in MySQL, which is dynamically generated through SQL queries, and is used to simplify complex queries and improve security. 1. The view does not store data and relies on actual tables to generate content dynamically; 2. The creation syntax is CREATEVIEW, which can encapsulate common query logic; 3. Common uses of views include simplifying multi-table connections, restricting sensitive data access, providing unified interfaces, and aggregating data display; 4. The views can be modified or deleted through ALTERVIEW or DROPVIEW; 5. When using views, you need to pay attention to performance issues, avoid nesting complex logic, and regularly check execution efficiency.
2025-07-04
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478
How to create a circular progress bar with CSS?
Article Introduction：Create an infrastructure using HTML and set progress values through custom attributes --progress; 2. Use CSS's conic-gradient to generate a colored fan background based on --progress; 3. Cut out the center area through pseudo-element::before and inset and border-radius to form a ring; 4. Optionally add a styled span tag as the center text tag; 5. The overall centering content is centered through flex layout, and the final effect is a 75% green fill and 25% gray remaining ring progress bar, and the progress value can be dynamically updated and animation effects can be achieved through JavaScript.
2025-08-05
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506
Example of a pagination component in Vue
Article Introduction：To implement reusable Vue paging components, the following key points need to be clarified: 1. Define props including the total number of lines, the number of lines per page and the current page number; 2. Calculate the total number of pages; 3. Dynamically generate the displayed page number array; 4. Process the page number click event and pass it to the parent component; 5. Add styles and interaction details. Receive data through props and set default values, use the computed attribute to calculate the total number of pages, use the method to generate the currently displayed page number array, render buttons in the template and bind click events to trigger the update:current-page event, listen to the event in the parent component to update the current page number, and finally highlight the current page number through CSS and control the button status to improve the user experience.
2025-07-26
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947
How to Check Which Tables Contain Data in a Database
Article Introduction：In database management, it is important to quickly identify the table of data containing data, which helps to investigate problems, maintain databases or understand the structure and use of the database. This article describes whether there is data in the check form in different relationship database management systems (RDBMS).
Postgresql
PostgreSQL uses pg_cataLog.pg_tables to dynamically generate query to check all the lines of all tables in the architecture:
Use PL/PGSQL block:
DO $ $
Declare
TBL Record;
Begin
For TBL in
Select schemaname, T
2025-01-29
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1228
How does a HashMap work internally in Java?
Article Introduction：HashMap implements key-value pair storage through hash tables in Java, and its core lies in quickly positioning data locations. 1. First use the hashCode() method of the key to generate a hash value and convert it into an array index through bit operations; 2. Different objects may generate the same hash value, resulting in conflicts. At this time, the node is mounted in the form of a linked list. After JDK8, the linked list is too long (default length 8) and it will be converted to a red and black tree to improve efficiency; 3. When using a custom class as a key, the equals() and hashCode() methods must be rewritten; 4. HashMap dynamically expands capacity. When the number of elements exceeds the capacity and multiplies by the load factor (default 0.75), expand and rehash; 5. HashMap is not thread-safe, and Concu should be used in multithreaded
2025-07-15
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1086
What are subqueries or nested queries in SQL?
Article Introduction：A subquery is a query statement nested in another SQL query and is often used to dynamically obtain values or sets of values for use by the main query. It can appear in SELECT, FROM, WHERE or HAVING clauses, and is most commonly compared in WHERE conditions, such as finding employees whose salary is higher than the average salary; subqueries can also be used to generate derivative tables, as field expressions, or perform existence checks; performance issues should be paid attention to when using them, especially the related subqueries may be repeated execution to affect efficiency; at the same time, to ensure that the return result type matches, a single-value comparison needs to return a value, and multiple-value comparisons can be handled by operators such as IN and EXISTS; appropriate use of alias and brackets can improve readability and avoid syntax errors; in some cases, JOIN operations can
2025-07-31
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567
Dave The Diver: How To Catch Spider Crabs
Article Introduction：In Dave The Diver, there are some creatures that are not easy to catch. Or, catch alive that is. The spider crab is one of those very species, making it seem like the only way to bring these crustaceans back up to land is to viciously crack them up w
2025-01-10
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865
Prepare for Interview Like a Pro with Interview Questions CLI
Article Introduction：Prepare for Interview Like a Pro with Interview Questions CLI
What is the Interview Questions CLI?
The Interview Questions CLI is a command-line tool designed for JavaScript learners and developers who want to enhance their interview
2025-01-10
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1492
Soft Deletes in Databases: To Use or Not to Use?
Article Introduction：Soft Deletes: A Question of DesignThe topic of soft deletes, a mechanism that "flags" records as deleted instead of physically removing them, has...
2025-01-10
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1086
Terraria: How To Make A Loom
Article Introduction：There are a lot of crafting stations that you can make in Terraria. This ranges from simple anvils to unique stations meant for one specific type of resource. Early into the game, you'll be able to make your own Loom, which is primarily used to make
2025-01-10
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1372
