SQL Learning 💻

When assigning unique identifiers to rows based on a specified order, three key functions come into play: ROW_NUMBER, RANK, and DENSE_RANK. Consider the following table: | Name | Score | |-------- |-------| | Alice | 90 | | Bob | 90 | | Carol | 85 | | David | 78 | ROW_NUMBER: The simplest of the three, ROW_NUMBER assigns a unique number to each row based on the specified order. Each row receives a distinct identifier, incrementing by one. Example:

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RANK: Assigns unique numbers, and in the case of ties, rows get the same rank, and the next rank is skipped.

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DENSE_RANK: Assigns ranks to rows with tied values, without skipping the next rank

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These functions help in organizing and analyzing data by providing distinct identifiers or ranks based on specified criteria. The example table illustrates how ROW_NUMBER, RANK, and DENSE_RANK operate in assigning order to rows with varying scores. (Note: This is 1/3 of the total number of articles; others are coming soon.)

Here's a snippet of code written in C:

for(int i=0;i<n;i++)
{
 for(int j=0;j<n;j++)
{
//some operation
}
}

How can I write something equivalent in SQL? Solution:Alias say, you are asked to count the frequency of each color occurring in the same table , so you can write something like this: select distinct color ,(select count(*) from colors where c.color=color) from colors c;

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You are given this database, your task is to output➡

Write a sql query to find the Joining date of Employee in YYYY-DAY-Date format.

Write a sql query to delete duplicate rows from a table.

Write a sql query to find the second largest number from table table_name and column number.

https://docs.microsoft.com/en-us/sql/t-sql/lesson-1-creating-database-objects?view=sql-server-ver15 Start your tutorial here

Find the Employees who hired in the Last n months. Write a SQL query for that. Send your queries in the discussion group.

Through this you can access a very good course on SQL for FREE.

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