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Data Definition Language (DDL) defines and reshapes the structure of a database, its schemas, tables, columns, constraints, indexes, views, sequences, and partitions. Unlike DML (which manipulates row data), DDL changes the blueprint those rows live in. Because DDL alters metadata, it can take strong...
SQL constraints protect data quality. They make sure every row has an ID, and things like email addresses don’t accidentally repeat, so your database stays consistent, reliable, and easy to query. Primary Key * The primary key uniquely identifies each record. * A primary key column can’t be e...
Data Manipulation Language (DML) is the part of SQL used to work with the data itself—adding it, looking it up, changing it, and removing it. If you think of your database as a set of labeled spreadsheets, DML is how you fill rows in, read them back, edit them, or clear them out. SQL Query is the fo...
SQL data types define the kind of values you can store in a database column. Choosing the correct data type is important because it affects storage, performance, and data accuracy. Every table column in SQL must have a data type assigned to it. Common SQL Data Types Numeric Data Types 1. INT...
What is a Database? A database is an organized collection of structured data designed to store information and make it easier to manage data efficiently. Modern database systems are built to store data, process transactions, and ensure data security while supporting a wide range of applications. Dat...
What is SQL? SQL stands for Structured Query Language. It is used to store information in databases which consist of tables that are collections of records or entities, organized into rows and columns. SQL is the tool that allows you to interact with this data. SQL is relevant in modern technologie...