Can you use UNIQUE KEY as a replacement for Primary Key ?
Both Keys are different. For Identifying each and every record in a table we use primary key. To apply additional uniqueness for other columns on the table we use Unique…
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SQL
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What are all the different attributes of indexes ?
The indexing has various attributes: Access Types: Value based search , range acess can be refered using Access types. Access Time: Time that is needed to find a data element…
What are the different types of SQL commands ?
DDL (Data Definition Language) DML (Data Manipulation Language) DCL (Data Control Language) TCL (Transaction Control Language) DDL(Data Definition Language) DDL is a syntax that is used for creating SQL commands.…
Difference between SQL and PLSQL
SQL PL/SQL SQL is structural query language for database. It has no variables. Pl/SQL is a programming language using SQL for database. It has variables and data types SQL has…
Char vs Varchar in SQL
Char VarChar Char data type is used for storing single character values It is a SQL Code that helps in storing variable character Used to store characters string of fixed…
What is Default constraint in SQL ?
Constraints are a certain set of rules used for processing data and limiting the type of data that can go into the table. The default constraint is used to define…
What are the different types of relationships in SQL ?
Data base collects different types of data that uses tables, record, and columns. For easy storage of data, a well-defined relationship is created between tables and databases. Data in a…
Types of indexes in SQL
There are various types of indexes in SQL server: Clustered Index Non-Clustered Index Column Store Index Filtered Index Hash Index Unique Index Clustered Index Rows of data are sorted and stored…
What is the difference between BETWEEN and IN operators in SQL ?
BETWEEN IN This condition allows you to check if given values are in the specified range. In operator is used for matching values in the given list of values. …
What is a join in SQL ? What are the types of joins ?
Data is stored in multiple tables that are related to each other in relational data bases like SQL Server, MySQL etc with a common key value. When we need to…
What are the different types of database management systems ?
Database Management System is classified into four types: Hierarchical Database It is a tree like structure where the data is stored in form of a tree. In this type of…
What is a Database ?
In computing, database is an organized collection of data stored which is accessed electronically. A database is usually controlled by Data Base Management Systems(DBMS). In a computer data is stored…
What is a primary key ?
In relational database primary key is a specific choice of minimal set of attributes that uniquely specify a relation. Primary key is a special realational database table column key that…
What is Normalization in SQL ?
It is a rule where larger tables are divided into smaller tables and they are linked using relationships. Process of organizing data in a data base is called as Normalization.…
What is SQL ?
SQL stands for Structured Query Language. It is used for interacting with databases. SQL is also known as standard query language which is used for maintaining relational database management systems(RDBMS).…
Lazy writer in Memory ?
Answer : Lazy write is an effect caused by the use of a write-back cache…
What is the difference between the SubQuery and Corelated SubQuery ?
Answer : The inner query is executed only once…
What is the Difference between join and union ?
Answer : The union operator combines the results of two or more queries into a single result set…
What is the difference between a HAVING CLAUSE and a WHERE CLAUSE ?
Answer : The HAVING clause sets conditions on the GROUP BY…
