Rahul Swami posts

SQL Tutorial ROLLUP and CUBE

rollup( ), cube( ) clause are used to calculate subtotal, grand total. it will generate subtotals for all combinations of the dimensions specified.

SQL ORDER BY Clause overview and examples

This tutorial shows use of Order by clause for sorting data either in ascending order or in descending order.

SQL Having Clause

The HAVING clause used because we are not allowed to use WHERE clause after GROUP BY clause. If we want to restrict something in a table then we are using HAVING clause followed by GROUP BY clause.


Group by clause is used to arrange similar data items into set of logical groups. If a column having same values in multiple rows then it will arrange those rows into a group. We can also use group by clause without using group functions.

Heatmap with lattice and levelplot

This post explains how to use levelplot( ) function to build heatmaps.

CSS Colors

Learn how to use color in CSS.

apply lapply tapply sapply Function in R

We will learn sapply(), lapply() and tapply() in R.

Getting a list of random numbers in normal distribution

A distribution of values that cluster around an average.

R Data Frames

data frame is used for storing data tables.

Multiple curves on the same plot

you will learn to plot more than one curve on a single plot in R.

R Bar Plot

you will learn to create bar plot for compare data visually.

3D Plot in R

you will learn to create 3D plots.

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