rdbms
General Functions in SQL
Functions in SQL enable we to perform feats such as determining the sum of a column or converting all the characters of a string to uppercase.
Joins in SQL
One of the most powerful features of SQL is its capability to gather and manipulate data from across several tables. Without this feature we would have to store all the data elements necessary for each application in one table. Without common tables we would need to store the same data in several tables. Imagine having to redesign, rebuild, and repopulate our tables and databases every time our user needed a query with a new piece of information. The JOIN statement of SQL enables us to design smaller, more specific tables that are easier to maintain than larger tables.
Sub Queries in SQL
A subquery is a query whose results are passed as the argument for another query. Sub queries enable us to bind several queries together.
Data Definition Language
A data definition language (DDL) is a computer language used to create and modify the structure of database objects in a database. These database objects include views, schemas, tables, indexes, etc. This term is also known as data description language in some contexts, as it describes the fields and records in a database table.
Data Manipulation Language
A DML or refers to a computer programming language that allows you to add, delete, and alter data in a database. A DML is typically a sub language of a larger database language like SQL, with the DML containing some of the language's operators.