Skip to content

Tag Archives: SQL-basics

Prerequisite – SQL Injection While checking for SQL injection we all discover various error messages. Let us figure out the basic cause behind each error… Read More
1. ALTER Command : ALTER SQL command is a DDL (Data Definition Language) statement. ALTER is used to update the structure of the table in… Read More
1. Procedures : A procedure is a combination of SQL statements written to perform a specified tasks. It helps in code re-usability and saves time… Read More
Lateral keyword represents a lateral join between two or more tables. It joins the output of the outer query with the output of the underlying… Read More
Prerequisite – DDL, DQL, DML, DCL and TCL Commands DDL: DDL is Data Definition Language which is used to define data structures. For example: create… Read More
Prerequisite: SQL | GROUP BY Error: Column ‘col’ is invalid in the select list because it is not contained in either an aggregate function or… Read More
Prerequisite – SQL Trigger | Student Database For example, given Library Book Management database schema with Student database schema. In these databases, if any student… Read More
Trigger: A trigger is a stored procedure in database which automatically invokes whenever a special event in the database occurs. For example, a trigger can… Read More
The Common Table Expressions (CTE) were introduced into standard SQL in order to simplify various classes of SQL Queries for which a derived table was… Read More
DISTINCT is useful in certain circumstances, but it has drawback that it can increase load on the query engine to perform the sort (since it… Read More
A role is created to ease setup and maintenance of the security model. It is a named group of related privileges that can be granted… Read More
Like in other programming languages, SQL also has certain datatypes available. A brief idea of all the datatypes are discussed below.   1. Binary Datatypes… Read More
In this article, we will see how to create, delete, and uses of the INDEX in the database. An index is a schema object. It is… Read More
In this article, we’ll be discussing Data Definition Language, Data Manipulation Language, Transaction Control Language, and Data Control Language. DDL (Data Definition Language) : Data… Read More
Sequence is a set of integers 1, 2, 3, … that are generated and supported by some database systems to produce unique values on demand.… Read More