SQL TYPES

Structured Query Language, or SQL, is divided into a number of different forms according to the function of the commands. When it comes to managing and modifying data in a relational database, each type has a distinct purpose. Data Definition Language is the first and possibly most fundamental type (DDL). Database objects including as tables, indexes, and schemas can have their structures defined or changed using DDL. CREATE, ALTER, DROP, and TRUNCATE are examples of common DDL commands. For instance, you define a new table and specify the columns and data types when you use CREATE TABLE. The ALTER TABLE command is used if you need to change the table later, like as by adding a new column. e Data Manipulation Language (DML), which concentrates on the actual data within database tables, is the next significant category. SELECT, INSERT, UPDATE, and DELETE are examples of DML commands. To get data (SELECT), create new records (INSERT), update current information (UPDATE), or delete it (DELETE), you utilize these commands on a daily basis. People frequently associate "SQL coding" with DML since it refers to the process of working with stored data. Data Control Language (DCL), which deals with access control and permissions, is another significant kind. Commands like GRANT and REVOKE are part of DCL. Database resources can be accessed or restricted using these commands. GRANT, for instance, can be used by an administrator to allow a user to read data from a table but not to change it. Conversely, REVOKE has the ability to eliminate those permissions. This kind is necessary to preserve security and safeguard private data in a database. Transaction Control Language (TCL) is closely related to DML and DCL. TCL is used to control database transactions in order to guarantee data consistency and integrity, particularly in systems that execute several tasks concurrently. The TCL commands COMMIT, ROLLBACK, and SAVEPOINT are frequently used. In essence, a transaction is a collection of SQL actions that should either all fail or all succeed together. For example, the withdrawal and deposit must take place simultaneously when moving funds across bank accounts. ROLLBACK makes guarantee that modifications are reversed in the event that one component fails. COMMIT completes the transaction if all goes according to plan. TCL is essential for preventing data corruption because it allows developers to control when and how changes are saved. Some SQL dialects (such as PL/SQL for Oracle or T-SQL for SQL Server) have procedural extensions in addition to these fundamental types that enable the use of control-of-flow logic like loops and conditionals, further enhancing SQL's functionality. Although they are frequently utilized in real-world applications, these are not included in standard SQL. Because it enables developers and database administrators to build more structured, secure, and effective code, knowing the various SQL types is crucial. Your database will continue to be responsive, well-structured, and simple to maintain if you use the appropriate SQL type for the job.