Articles tagged with: SQL
This article shows how to write/run/execute custom SQL queries in Magento 2. We need to instantiate class Magento\Framework\App\ResourceConnection for this. You have to inject this resource class in your module’s Block/Model/Controller class constructor. After that, you can use that object to run custom sql queries.
In this example, I will simply be using object manager to instantiate the resource class.
Here is a quick tip to add OR query and AND query to collection object. I am implementing this on product collection.
Getting product collection
Some definitions of foreign key:-
A FOREIGN KEY in one table points to a PRIMARY KEY in another table.
A foreign key is a field in a relational table that matches the primary key of another table. The foreign key can be used to cross-reference tables. A table may have multiple foreign keys, and each foreign key can have a different referenced table.
You have created a custom module.
You have entered certain data in your database.
You need to show the data randomly.
The JOIN keyword is used in an SQL statement to query data from two or more tables, based on a relationship between certain columns in these tables. [@via w3schools]
A SQL JOIN clause combines records from two or more tables in a database. It creates a set that can be saved as a table or used as is. A JOIN is a means for combining fields from two tables by using values common to each. ANSI standard SQL specifies four types of JOINs: INNER, OUTER, LEFT, and RIGHT. In special cases, …
Cannot insert the value NULL into column ‘SourceId’, table ‘Advisory.dbo.AdvDocSource’; column does not allow nulls. INSERT fails.
The statement has been terminated. The ‘CompanyAdd’ procedure attempted to return a status of NULL, which is not allowed. A status of 0 will be returned instead.
This error occurs because the ‘SourceId’ column in my table is primary key and it is set to not null. i.e. it doesn’t allow null entries. And I have not made it auto increment.