---
title: "Declarative Schema in Magento 2.3.x or later"
url: "https://dolphinwebsolution.com/declarative-schema-in-magento-2-3-x-or-later"
date: "2021-03-22T06:20:09+05:30"
modified: "2023-08-28T05:48:12+05:30"
author:
name: "Payal Patel"
categories:
- "Magento"
word_count: 2732
reading_time: "14 min read"
summary: "In this tutorial, we teach you how to create/drop a table using Declarative Schema. Magento 2.3 implemented a new feature called Declarative Schema, in previous Magento versions create setup script..."
description: "In this tutorial, we teach you how to perform create, drop or other operations using Declarative Schema. Magento 2.3 implemented a new feature called Declara..."
keywords: "declarative schema,declarative schema in magento,magento 2 declarative schema,Declarative Schema in Magento 2.3, Magento"
language: "en"
schema_type: "Article"
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---
# Declarative Schema in Magento 2.3.x or later
_Published: March 22, 2021_
_Author: Payal Patel_
> In this tutorial, we teach you how to create/drop a table using Declarative Schema. Magento 2.3 implemented a new feature called Declarative Schema, in previous Magento versions create setup script for install, upgrade and uninstall table or data. Declarative Schema facilitates the installation and upgrading of code that is contained within a single XML file. We can perform the following operations with DDL(Data Definition Language) and DML(Data Manipulation Language).
In this tutorial, we teach you how to perform create, drop or other operations using Declarative Schema. [Magento 2.3](https://devdocs.magento.com/guides/v2.3/release-notes/bk-release-notes.html) implemented a new feature called Declarative Schema, in previous Magento versions [create setup script for install, upgrade and uninstall table or data](https://dolphinwebsolution.com/how-to-create-install-upgrade-uninstall-script-in-magento-2).
Declarative Schema facilitates the installation and upgrading of code that is contained within a single XML file. We can perform the following operations with DDL(Data Definition Language) and DML(Data Manipulation Language).
### **Step 1:** Create Table
Create **db\_schema.xml** file in **app/code/Dolphin/MyModule/etc** with the following code.
```
```
In the above code, the **Table Node** contains the following attributes,
- **Name:** Name of the table name
- **Engine:** This the SQL engine, must be required value InnoDB or memory
- **Resource:** This value must be default, checkout or [sales](https://dolphinwebsolution.com/best-magento-2-extension-to-boost-sales)
- **Comment:** Table comment
The table node three different types of subnodes,
- **column**
- **constrains**
- **index**
**Column:** A column node can contain the following attributes,
- **Type:** The column type contains the blob (such as includes blob, mediumblob, longblob), boolean, date, datetime, int (int, smallint, bigint, tinyint), real (decimal, float, double, real), text (text, mediumtext, longtext), timestamp, varbinary and varchar.
- **Name:** Name of the column name
- **Padding:** The size of the integer column
- **Unsigned:** The column contains positive and negative values or only positive values
- **Nullable:** Tha column can be nullable
- **Comment:** Column comment
- **Length:** The length of the column
**Constrains:** The constrains node can contain the following attributes,
- **Type:** primary, unique and foreign key
- **ReferenceId:** A custom identifier used only for relation mapping in db\_schema.xml files
If you use **Magento version 2.3** something then you can need to run the following command for **db\_whitelist\_schema.json** file.
```
php bin/magento setup:db-declaration:generate-whitelist --module-name=Dolphin_Mymodule
```
**db\_whitelist\_schema.json** file created after run above command in **app/code/Dolphin/MyModule/etc** folder.
Now, run the following upgrade command,
```
php bin/magento setup:upgrade
```
### **Step 2:** Drop Table
Let’s start with the drop table remove the entire table node in **db\_schema.xml** file, follow the below code.
```
-
```
### **Step 3:** Rename Table
Let’s start with the rename table in **db\_schema.xml** file, follow the below code.
```
```
In this above code you can see **onCreate** attribute added in **** attribute and **migrateDataFromAnotherTable()** function. Please pass the parameter with old table name in **migrateDataFromAnotherTable()**.
**Note:** It is not possible to migrate data from another table and renaming columns at the same time.
### **Step 4:** Add a column to the table
We are going to new add a column in the table in **db\_schema.xml** file with the following code.
```
```
### **Step 5:** Drop a column to the table
Now, we remove the company column by remove that column node.
```
```
### **Step 6:** Change the column type
We can change column type varchar to text.
```
```
### **Step 7:** Rename the column name
Let’s we can change the column name with the following code.
```
```
You can see in the above code the column name message to comment with the **migrateDataFrom()** function using the old column name message.
### **Step 8:** Add an Index
In the following code add an Index to the **entity\_id**.
```
```
In the above code INDEX\_REFERENCE\_ID index to the custom\_table table.
### **Step 9:** Create a foreign key
In the below example, add a new foreign key using the constraint node.
```
```
### **Step 10:** Drop a foreign key
In the below example, remove the foreign key using **ADD\_REF\_FOR\_CUSTOM\_TABLE** by deleting the constraint node. But, when declaring the constraint node to the other module then use the **disable** attribute with value **true**.
```
```
You can see in the referenceId **DOLPHIN\_MYMODULE\_CONTACT\_ENTITY\_ID\_DOLPHIN\_MYMODULE\_CUSTOM\_CUSTOM\_ID** is the **ADD\_REF\_FOR\_CUSTOM\_TABLE**.
### **Step 11:** Recreate a foreign key
We have to add **disable** attribute as per **Step 10**. Check the following example.
```
```
We hope our guide is very effective for you. If any questions, please feel free to leave a comment below. In the next tutorial, you will help with [how to create Models, ResourceModels, and Collections in Magento 2](https://dolphinwebsolution.com/models-resource-models-and-collections-in-magento-2).
---
_View the original post at: [https://dolphinwebsolution.com/declarative-schema-in-magento-2-3-x-or-later](https://dolphinwebsolution.com/declarative-schema-in-magento-2-3-x-or-later)_
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_Generated: 2026-08-26 06:54:29 UTC_