Understand what is a schema in SQL

SQL schema

When we design any kind of application, the plan is processed according to the client-side language, server-side language, and a database management system. Whether it’s a small and large organization/application, Database management will be associated with the subject application, which is managed by the SQL commands. Know the insight of what is schema in SQL?

SQL is a specific language designed to manage the relational database tables and its data, using the SQL commands, you can change the data of database tables, alter the tables, copy the data and also can enter the new data inside the database. To maintain the data of the database we practice some syntax and queries.

On the behavior and operation of SQL, it is classified into four different categories that are DDL(Data Definition Language), DML(Data Manipulation Language), DCL(Data Control Language), TCL. 

Functional Benefits of SQL

  • You can create a new table and delete the unnecessary data from the database.
  • SQL proposed a special manner of commands and queries to manipulate and define the data.
  • By using SQL Data you have the ability to arrange the data according to your convenience.
  • SQL language plays an important role to bind the libraries, objects, modules, and mage the functionality among all.
  • SQL’s DDL command is responsible for creating the structure of Data inside the database.
  • As the name suggests the DML command responsible for changing the predefined data stored in the database.
  • DCL is responsible for securing your data from hacking and restricting unauthorized access.
  • SQL works as an interface between the client-server so the user can interact with the database, front-end, and back-end.
  • SQL is popular for interactivity and portability.
  • The server and database are presented in the form of a three-tier architecture.

What is a schema in SQL?

The group of Database objects known as the SQL Schema. Each database has its credential, one who designed and managed the schema is considered as Schema Owner. The schema is a logical model of organized data. One who knows the credentials of the database can access the schema of the SQL.

One schema is connected to the one database, but one database has many different schemas. A Schema is considered as an independent entity. The schemas and separate namespaces can be similar to data objects.

Each table can store numerous objects. To make you understand what is a schema in SQL, we are giving you an example:

Username is EMPLOYEE1, the table name is EMP_TABLE. EMPLOYEE1 will be considered as the schema name also formed as the owner of the table.

Schema Database

The set of logical objects formed the database schema. To define the schema, an RDBMS supported formal language is used. The database schema is operated by the formulas, these formulas are considered as the integrity constraints. In the case of recursive references, you can take the reference of the same foreign key to create two or more tables.

The formulas use a similar language to maintain the capabilities of schema parts. The design and implementation of two schemas may differ.

Schema (SQL Server)

Procedures, Functions, Triggers, Tables, View, and Index are the different structures that are contained by the database. In other words, SQL Database Schema is a collective form of logical objects. The database and SQL schemas have a similar name and the user has the access to control and authorization of the database. 

The set of logical structures is managed by the schema owners. You can transfer the ownership of the schema. In SQL Server, one schema is connected to only one database but a database gives you the opportunity to create as many schemas you want to use to fulfill your purposes. Schemas contain a unique independent entity.

In DBMS administration, Schema is considered as a secure way of organizing unique objects for different applications purposes. Create as many objects you want to store in a schema. The schemas and databases are similar to each other.

The schema permits you to create, segregate, and access the objects of the database, its an authorized and secure medium.

For example: here, carstore is a database that has two schemas sales and models. You can use this format to access the objects:

Schema_name .object name 

as models .orders.




The schemas that have been defined by two different names can contain a similar name for the table.

Built-in SQL Schemas

SQL Server has introduced the predefined schema, which is similar to the built-in roles and users that is used for backward compatibility. You can check the following built-in schema:

dbo

quest

sys

INFORMATION_SCHEMA

There’s a condition defined on the above-mentioned schemas that the object can’t be removed or dropped. If you drop the schema, it won’t be visible in another database.

dbo Schema

The database has a default schema that is known as dbo schema, the ownership of dbo schema belongs to dbo user. We use the CREATE_USER command to create the schema user, the dbo schema is created by default. 

When the first schema is located by default it resolves the object names. By using the SCHEMA_NAME command user can rename the schema of the database.

How to create a Schema?

To create a schema, you can follow the following SQL syntax.

CREATE SCHEMA

[write schema name here]

[AUTHORIZATION owner_name]

[DEFAULT CHARACTER SET character_set_name]

[PATH schema_name[,……]]

[ANSI CREATE statements[…….] ]

[ANSI GRANT statements[…….] ];\

Suppose, we are operating the command CREATE_SCHEMA

Type the “production_items” as a schema name to define for the CREATE_SCHEMA module.

The “AUTHORIZATION” keyword is specified for the schema owner. If the authorized user name is not specified, the schema name will be similar to the database user name.

Use this SQL command

CREATE SCHEMA production_orders > GO

When the GO statement is executed, production_orders schema will be created. Inside this schema, you can create the objects. 

Follow the following set of lines as a syntax to create a table inside the production_orders

CREATE TABLE items(

Item _id int PRIMARY KEY IDENTITY,

Order_id INT NOT NULL,

DESCRIPTION VARCHAR(200),

Created_at DATETIME2 NOT NULL

);

SQL server management studio will provide the way to create a new schema, you can use the following steps:

  • Go to the object explorer window and click on the database folder.
  • Locate the database schema arranged under the database folder option.
  • Use the right click button > Security folder > New > Select Schema.
  • Schema Owner Box > DB user name.
  • Hit the OK button.

After performing these steps you will get a new schema with your opted name.

Guide to create a schema SQL server management studio

  • Locate the object explorer > database folder.
  • Step down to create a DB schema.
  • Right click > security folder > New >select schema.
  • Enter an appropriate name for the schema in the dialog box.
  • Go to the owner box to type the name and specify the authorization > search > search roles and user.
  • Hit the ok button. Now you have owned the schema in SQL server management studio.

How to Alter a schema?

If one wants to change the name of a schema or to occupy a new owner, the ALTER_SCHEMA command is used. Before operating this command, ensure that the owner should already exist. One has to type the following syntax:

[OWNER TO new_user_name]

How to drop a schema?

If you want to drop an existing database, use the DROP DATABASE command, we will just interchange the word “DATABASE” with the “SCHEMA” and execute the command as follows:

DROP SCHEMA schema name

You have the option to drop all the tables and database by operating the following command:

AUTHORIZATION DROP SCHEMA database name;




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