database

问题 I'm building a Flutter app where I would like to keep the data offline. I'm capturing an image using the camera or gallery image picker and able to store that image into a File image variable. File _avatarImg; void _getImage(BuildContext context, ImageSource source) { ImagePicker.pickImage( source: source, maxWidth: 400.0, maxHeight: 400.0, ).then((File image) { _avatarImg = image; }); } This works perfectly however my question is, how would I go about storing this image for persistence?

问题 I'm building a Flutter app where I would like to keep the data offline. I'm capturing an image using the camera or gallery image picker and able to store that image into a File image variable. File _avatarImg; void _getImage(BuildContext context, ImageSource source) { ImagePicker.pickImage( source: source, maxWidth: 400.0, maxHeight: 400.0, ).then((File image) { _avatarImg = image; }); } This works perfectly however my question is, how would I go about storing this image for persistence?

问题 | 1 | 2 | 3 | +------------+ | A | B | C | | D | E | F | | G | H | I | System.Data.DataTable dt = new DataTable(); dt.Columns.Add("1"); dt.Columns.Add("2"); dt.Columns.Add("3"); dt.Rows.Add(new object[] { "A", "B", "C" }); dt.Rows.Add(new object[] { "D", "E", "F" }); dt.Rows.Add(new object[] { "G", "H", "I" }); int? index = null; var rows = new System.Data.DataView(dt).ToTable(false, new[] {"1"}).Rows; for (var i = 0; i < rows.Count; i++) { if (rows[i].ItemArray.FirstOrDefault() as string ==

问题 Currently I use while(true) and Thread.sleep() for checking for new records in the db and execute java code. Here is an example: public class StartCommands implements Runnable{ private Active_Job activeJob; Runnable execute_command; public StartCommands(){ activeJobs = new Active_Job(); } @Override public void run(){ int jobId = 0; while(true){ //access the db and get one row from the table by the status jobId = activeJobs.get(Status.NEW); if (jobId > 0){ activeJob.updateStatus(Status.INIT);

问题 I'm new to Laravel.I'm trying to create database in Laravel. I tried in console with: Schema::create But it's giving 'command not found'. What should I install or how to create database? 回答1: First you have to set database name,username and password in database.php in config folder.it look like 'connections' => [ 'sqlite' => [ 'driver' => 'sqlite', 'database' => storage_path('database.sqlite'), 'prefix' => '', ], 'mysql' => [ 'driver' => 'mysql', 'host' => env('DB_HOST', 'localhost'),

问题 I'm new to Laravel.I'm trying to create database in Laravel. I tried in console with: Schema::create But it's giving 'command not found'. What should I install or how to create database? 回答1: First you have to set database name,username and password in database.php in config folder.it look like 'connections' => [ 'sqlite' => [ 'driver' => 'sqlite', 'database' => storage_path('database.sqlite'), 'prefix' => '', ], 'mysql' => [ 'driver' => 'mysql', 'host' => env('DB_HOST', 'localhost'),

问题 Many examples out there advocate explicit rollback of database transactions, along the lines of: using (var transaction = ...) { try { // do some reading and/or writing here transaction.Commit(); } catch (SqlException ex) { // explicit rollback transaction.Rollback(); } } However, I tend to do this: using (var transaction = ...) { // do some reading and/or writing here transaction.Commit(); } When an exception occurs, I'm just relying on the implicit rolling back of transactions that aren't

问题 I've been doing some web development work in PHP recently which has led me to study up on the language in general. So far I have not needed to use it to interact with a database, but I know it provides a lot of convenient functions for doing so. Although I know basic SQL and have worked with basic manipulation of data in a database, I don't understand how web developers who base their websites around PHP/Javascript/SQL are able to manage users modifying the same data at the same time. For

问题 I've been doing some web development work in PHP recently which has led me to study up on the language in general. So far I have not needed to use it to interact with a database, but I know it provides a lot of convenient functions for doing so. Although I know basic SQL and have worked with basic manipulation of data in a database, I don't understand how web developers who base their websites around PHP/Javascript/SQL are able to manage users modifying the same data at the same time. For

问题 I've been doing some web development work in PHP recently which has led me to study up on the language in general. So far I have not needed to use it to interact with a database, but I know it provides a lot of convenient functions for doing so. Although I know basic SQL and have worked with basic manipulation of data in a database, I don't understand how web developers who base their websites around PHP/Javascript/SQL are able to manage users modifying the same data at the same time. For