Introduction
Data is one of the most valuable resources in today’s Information Age. Depending on the interests, you can opt for a business analyst certification from Jigsaw Academy to advance ahead in your career. Most of the data that businesses use are stored in large databases. In the next part, we shall discuss what are DML commands and DML queries.
A relational database management system (RDBMS) is a type of database that stores data in tables with rows & columns and can be linked to other databases. Structured Query Languages (SQL) are among the most common ways to interact with relational database management systems (RDBMS). The commands used to communicate with the database using standard SQL are divided into several sub-languages. Depending on the provider and their SQL implementation, these sub-languages can be referred to in various ways. Two main categories are
- Data Description Language (DDL) – These statements manage the objects within the database. They are used to create users, tables, databases, constraints, etc. For example, CREATE, DROP, RENAME, ALTER.
- Database Manipulation Language (DML) – DML commands are used for data management within the database. For example, INSERT, UPDATE, DELETE
Now, let’s move on to DML commands in SQL.
List of DML commands in SQL.
DML commands are a component of SQL that is used to make changes in the databases. It is used to add new data in the table, change the record’s data in a table, or delete the data of a record in a table.
There are two types of DML commands: procedural and nonprocedural. Procedural DML commands define what data is required and how you will obtain it. Nonprocedural DML specifies only what data is required.
Here is a list of DML commands:
- SELECT – retrieve records from the table/database
- INSERT – to insert/add new records in a table
- UPDATE – modify/update existing records in a table
- DELETE – remove unwanted rows from the table
- MERGE – to perform insert, update and delete operations conditionally.
- CALL – call a PL/SQL or Java subprogram
- LOCK TABLE – control concurrency
SELECT
This DML command is used to select a set of data or information from the table. With this command, we can run queries on the table to retrieve information or view it. Syntax of this command depends on the requirement and is used with conditions and clauses.
The syntax for displaying all the information in the table is
SELECT * FROM <table_name> ;
Syntax to display specific information from the table is
SELECT <attribute>, ….., <attribute n> FROM <table name>;
INSERT
This command is used to add new records to the table. There are 2 methods of using these commands.
Syntax 1: When using this syntax, the order of the columns where data is inserted does not matter as we are specifying the column names.
INSERT INTO <table name> (column1_name, column2_name,……..) VALUES (<value 1>, … <value n>);
Syntax 2: While using this syntax, the order of the columns in the table matter. Values will be automatically added to the columns in the table in the sequence as mentioned in the command.
INSERT INTO <table name> VALUES (<value 1>, … <value n>);
UPDATE
This command is used to change or modify data in the table. The syntax is
UPDATE <table name> SET <attribute> = <expression> WHERE <condition>;
It changes the values of the selected columns to the new values where the specified condition is satisfied.
WHERE clause is important to avoid updating all the rows/columns.
DELETE
This command is used to delete a record or data from the table. The syntax of this command is
DELETE FROM <table name> WHERE <condition>;
This will delete the value/data from the table where the specified condition is met. WHERE clause is important to avoid deletion of all the data from the table.
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MERGE
MERGE command allows you to perform inserts, updates and deletes all in one transaction without writing separate logic for each. The SQL MERGE statement was introduced in SQL Server 2008, giving database programmers a lot of versatility to simplify their code around the INSERT, UPDATE, and DELETE statements.
Conclusion
We hope you have understood the key differences between DML and DDL commands. When dealing with large data sets or relational databases, SQL is the standard language for retrieving, updating, inserting and deleting data. It helps you better understand and analyses documents that contain database results and perform a more in-depth study of data contained in relational databases. Hence knowledge of DML commands in MySQL is a necessary and desirable skill for business analytics professionals. Knowing SQL and relational databases can help them better understand data flow in information systems by making it easier to generate reports and tailor them to their needs. It also helps them to interact more effectively with developers and database managers.
Getting the right skill sets is important for beginning a career in the field of data analytics. Institutions like Jigsaw Academy provide online business analytics courses that will provide you with a business analytics certification.
