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Explain group By clause in SQL?
Group By clause in SQL: The GROUP BY clause can be used in a SELECT statement to collect data across multiple records and group the results through one or more columns.
The syntax for the GROUP BY clause is:
SELECT column1, column2, ... column_n, aggregate_function (expression)FROM tablesWHERE predicatesGROUP BY column1, column2, ... column_n; aggregate_function could be a function like as SUM, COUNT, MIN, or MAX.
Explain the two types of participation constraint. 1. Total: The participation of an entity set E in a relationship set R is said to be total if each entity in E participates i
1. Staff(staffID, firstName, lastName, availabilityID, experience, phone, mobile, email); 2. Availability(availabilityID, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday,
Define Timestamp ordering Ans In timestamp-based method, a serial order is made among the concurrent transaction by assigning to every transaction a unique nondecreasing number
Using Literal Character String Example: To print IS A as one string with column name employee SELECT ENAME || ' IS A ' || JOB AS "EMPLOYEE" FROM EMP;
What is a shadow copy scheme? It is simple, but efficient, scheme known as the shadow copy schemes. It is based on making copies of the database called shadow copies that singl
List out various user authorization to modify the database schema. a) Index authorization b) Resource authorization c) Alteration authorization d) Drop authorizat
What is candidate key? Candidate Key - A candidate key of an entity set is a minimal superkey, which uniquely identifies each row in the relation.
Whenever the LIMIT clause will be used? LIMIT is used for the following kinds of problems: 1) Answering questions about first or last and largest or smallest 2) Splitting
What's the difference between a primary key and a unique key? Both primary key and unique key enforces uniqueness of the column on which they are explained. But by default prim
What is OMR? OMR (Optical Mark Recognition) is the translation of marks - or the absence of marks - but not the shape of the mark on forms that have small circles ("also called
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