Create the rooms table: CREATE TABLE rooms ( ) Code language: SQL (Structured Query Language) ( sql ) Create the buildings table: CREATE TABLE buildings (īuilding_no INT PRIMARY KEY AUTO_INCREMENT, The following are steps that demonstrate how the ON DELETE CASCADE referential action works. You also want the rows in the rooms table that refers to building number 2 will be also removed. WHERE building_no = 2 Code language: SQL (Structured Query Language) ( sql ) 2 in the buildings table as the following query: DELETE FROM buildings For example, when you delete a row with building no. When you delete a row from the buildings table, you also want to delete all rows in the rooms table that references to the row in the buildings table. The relationship between the buildings and rooms tables is one-to-many (1:N) as illustrated in the following database diagram: A room would not exist without a building. However, each room belongs to one only one building. In this database model, each building has one or many rooms. Suppose that we have two tables: buildings and rooms. Let’s take a look at an example of using MySQL ON DELETE CASCADE. However, MySQL provides a more effective way called ON DELETE CASCADE referential action for a foreign key that allows you to delete data from child tables automatically when you delete the data from the parent table. In the previous tutorial, you learned how to delete data from multiple related tables using a single DELETE statement. The DB facade provides methods for each type of query: select, update, insert, delete, and statement.Summary: in this tutorial, you will learn how to use MySQL ON DELETE CASCADE referential action for a foreign key to delete data from multiple related tables. Once you have configured your database connection, you may run queries using the DB facade. It is up to you to decide if this is the desired behavior for your application. This ensures that any data written during the request cycle can be immediately read back from the database during that same request. If the sticky option is enabled and a "write" operation has been performed against the database during the current request cycle, any further "read" operations will use the "write" connection. The sticky option is an optional value that can be used to allow the immediate reading of records that have been written to the database during the current request cycle. When multiple values exist in the host configuration array, a database host will be randomly chosen for each request. The database credentials, prefix, character set, and all other options in the main mysql array will be shared across both connections. So, in this case, 192.168.1.1 will be used as the host for the "read" connection, while 192.168.1.3 will be used for the "write" connection. You only need to place items in the read and write arrays if you wish to override the values from the main mysql array. The rest of the database options for the read and write connections will be merged from the main mysql configuration array. The read and write keys have array values containing a single key: host. Note that three keys have been added to the configuration array: read, write and sticky. After the database has been created, you may easily configure your environment variables to point to this database by placing the absolute path to the database in the DB_DATABASE environment variable: You can create a new SQLite database using the touch command in your terminal: touch database/database.sqlite. SQLite databases are contained within a single file on your filesystem. However, you are free to modify your database configuration as needed for your local database. Examples for most of Laravel's supported database systems are provided in this file.īy default, Laravel's sample environment configuration is ready to use with Laravel Sail, which is a Docker configuration for developing Laravel applications on your local machine. Most of the configuration options within this file are driven by the values of your application's environment variables. In this file, you may define all of your database connections, as well as specify which connection should be used by default. The configuration for Laravel's database services is located in your application's config/database.php configuration file.
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