DML stands for Data Manipulation Language. Tables and formulas are helpful when communicating with data stored up to a point in a database through SQL (Structured Query Language), but a time comes when we actually want to execute some fairly complicated data interactions. We will also need the Data Manipulation Language in that situation. DML is a way to inform a database precisely what we want it to do by conversing in a manner that it has been built to comprehend from scratch. When it comes to interacting with existing data, whether adding, moving, or deleting data, it provides a convenient way to do so.
Database Management System offers a framework of functions or dialects to modify or alter the data, called the Data Manipulation Language. Data manipulation could be done perhaps by typing SQL queries or by using, a typically called Query-by-Example graphical interface. These declarations are used to modify the data found in the tables. These declarations are going to work on results. There is no relation with the structure of the tables for these statements. Data manipulation includes introducing data into tables, altering the table’s data, and deleting the data from the table.
Transaction control is required for the DML statements. Any modification that a DML statement makes to the database will be called a transaction. Any adjustment made by the DML statement must, therefore, be controlled by TCL statements (Transaction Control Language). DML is a subset of SQL statements that alter the information stored in tables. As, it mainly concentrates on database performance, as well as it utilizes HDFS (Hadoop Distributed File System) storage’s append-only nature.
Types of Data Manipulation Language
There are basically two types of Data Manipulation Language. These are mentioned below. We have described them in the difference between format.
- High-Level or Non-Procedural DML
- Low-Level or Procedural DML
High-Level or Non-Procedural DML vs Low-level or Procedural DML
It is also labelled as set-at-a-time or series oriented DML.
It is also labelled as track-at-a-time DML.
It can be used on its own for precisely specifying complex operations in the database.
It must be integrated to a general-purpose programming language.
It is prescriptive in nature.
It is indispensable in nature.
It demands that a user must clearly state which data is needed without clarifying how and when to obtain those data.
It demands that a user must clearly state which data is needed and how to obtain those data.
For Example: Every SQL statement is a prescriptive command.
For Example: DB2’s SQL PL, Oracle’s PL/SQL.
Characteristics of DML
It performs interpret-only data queries. It is used in a database schema to recall and manipulate the information. DML It is a dialect which is used to select, insert, delete and update data in a database. Data Manipulation Language (DML) commands are as follows:
This command is used to get data out of the database. It helps users of the database to access from an operating system, the significant data they need. It sends a track result set from one tables or more.
FROM <table_name>; Example:
where due_fees <=20000;
This command is used to enter the information or values into a row. We can connect one or more records to a single table within a repository using this instruction. This is often used to connect an unused tag to the documents.
INSERT INTO <table_name> ('column_name1' <datatype>, 'column_name2' <datatype>)
VALUES ('value1', 'value2'); Example :
INSERT INTO students ('stu_id' int, 'stu_name' varchar(20), 'city' varchar(20))
VALUES ('1', 'Nirmit', 'Gorakhpur');
This command is used to alter existing table records. Within a table, it modifies data from one or more records. This command is used to alter the data which is already present in a table.
SET <column_name = value>
WHERE condition; Example:
SET due_fees = 20000
WHERE stu_name = 'Mini';
It deletes all archives from a table. This command is used to erase some or all of the previous table’s records. If we do not specify the ‘WHERE’ condition then all the rows would be erased or deleted.
DELETE FROM <table_name>
WHERE <condition>; Example:
DELETE FROM students
WHERE stu_id = '001';
Advantages of DML
- DML statements could alter the data that is contained or stored in the database.
- It delivers effective human contact with the machine.
- User could specify what data is required.
- DML aims to have many different varieties and functionalities between vendors providing databases.
Disadvantages of DML
- We cannot use DML to change the structure of the database.
- Limit table view i.e., it could conceal some columns in tables.
- Access the data without having the data stored in the object.
- Unable to build or erase lists or sections using DML.
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