Found a total of 10000 related content
HTML `select` `multiple` Attribute for Multi-Selection
Article Introduction：To implement the drop-down menu multiple selection function in HTML, 1. Add multiple attribute to the tag; 2. When submitting data, add [] after the name attribute so that the server can receive the array; 3. You can get the selected value through the querySelectorAll or selectedOptions attributes of JavaScript; 4. Pay attention to browser style differences, mobile compatibility and default expansion issues. For example: PHP can receive arrays through $_POST['colors'], and JavaScript can obtain values using Array.from(selectElement.selectedOptions).map.
2025-07-22
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987
MySQL complete code example of combining multiple pieces of data into one
Article Introduction：MySQL data merging is mainly implemented through the GROUP_CONCAT function and the JSON function. 1. Use the GROUP_CONCAT function to concatenate multiple records into strings, control the order and separator through ORDERBY and SEPARATOR, and GROUPBY specifies the grouping basis; 2. For complex data structures (such as JSON), use the JSON_ARRAYAGG function to merge multiple JSON objects into JSON arrays, which requires support from MySQL 5.7 or higher. The selection method depends on the data structure and complexity. Pay attention to the GROUP_CONCAT length limit and choose the optimal solution according to the actual situation.
2025-04-08
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1033
What is the significance of the 'Server' selection dropdown if multiple MySQL servers are configured?
Article Introduction：The "Server" drop-down menu in MySQL tool is selected to allow you to specify the database instance of the current operation to avoid misoperation. This feature is particularly important when you manage multiple environments (such as development, testing, and production); common uses include security testing code changes, differentiated permission management, and independent monitoring of performance; when switching servers, the application will load corresponding connection information based on the selected entry and establish a new connection; if you do not switch manually, the application will continue to use the previous connection, which can easily lead to misoperation; best practices include confirming server selection, clear naming, restricting permissions, using visual prompts or memo tags.
2025-07-18
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641
HTML `multiple` Attribute for File Uploads
Article Introduction：When uploading HTML files, multiple attributes can be used to achieve multi-file selection. Just add the multiple attribute to the tag, for example, the user can hold down Ctrl or Shift multiple selection files. To facilitate the backend to recognize as an array, it is recommended to set the name attribute to name="files[]". Mainstream browsers support this property, but old IE versions (such as IE10 and below) are incompatible. If necessary, Flash or third-party libraries can be used instead. The backend needs to receive data in an array, for example, PHP uses $_FILES['files']['name'], Node.jsExpress is used with mult.array
2025-07-17
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772
Bootstrap 5 offcanvas navbar example
Article Introduction：How to create and optimize OffcanvasNavbar for Bootstrap5? 1. Use the built-in offcanvas component to combine navbar, and build the basic structure by adding key categories such as navbar-expand-lg, offcanvas, data-bs-toggle, etc.; 2. In order to make offcanvas better adapt to different devices, use the d-lg-none control button to only display on the small screen, and cooperate with navbar-expand-lg to control navigation responsive expansion; 3. Frequently asked questions to optimize the optimization of the menu item: add data-bs-dismiss to achieve automatic closing of offcanvas after clicking, and add bg-da
2025-07-22
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379
