SQL:
- The Structured Query Language (SQL) is the language of databases.
- All modern relational databases, including Access, FileMaker Pro, Microsoft SQL Server and Oracle use SQL as their basic building block.
- In fact, it’s often the only way that you can truly interact with the database itself.
- All of the fancy graphical user interfaces that provide data entry and manipulation functionality are nothing more than SQL translators.
- They take the actions you perform graphically and convert them to SQL commands understood by the database.
- SQL is Similar to English
- Fortunately, at its core, SQL is a simple language.
- It has a limited number of commands and those commands are very readable and are almost structured like English sentences.
SQL Commands:
SQL commands are instructions. It is used to communicate with the database. It is also used to perform specific tasks, functions, and queries of data.
Types of SQL Commands:
The Data Definition Language (DDL) contains the commands used to create and destroy databases and database objects.
- Create
- Alter
- Drop
- Truncate
After the database structure is defined with DDL, database administrators, users can utilize the Data Manipulation Language (DML) to insert, retrieve and modify the data contained within it.
- Insert
- Update
- Delete
Data Query Language (DQL) contains commands to perform querying and retrieving data from table.
- Select
While Data Control Language contains commands to secure and control access to database and its objects.
- Grant
- Revoke
TCL means Transaction Control Language. These SQL Server TCL commands will control the Transactions.
TCL commands can only use with DML commands like INSERT, DELETE and UPDATE only.
- Commit
- Rollback
- Savepoint
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