Tag: Graphs

I wasn’t sure I was to go this far. After catching breath the following have been added to Generic, auto scaling, scaled SQL graphs, and these will conclude my current hacks:

• Displaying X-axis min/max values.
• Support for Y-axis values precision.
• Support for pre-defined scale range.

The addition of the above makes for presentable, usable graphs. See also sample graphs at the end of this post.

Step 8: adding X-axis values

I add minimum/maximum X-scale values to the graph. What was just ordering_column before, now turns to be the x in the y = f(x) function. Continue reading » “Auto scaling, scaled SQL graphs concluded”

In Rotating SQL graphs horizontally, I have shown how to rotate an ASCII SQL graph into horizontal position.

I was dissatisfied with some parts of the solution, which I will show now how to fix:

• I had to manually scale the graph values so as to fit nicely into screen.
• I had to rely on hard coded scaling schemes.
• I had to rely on hard coded column names.
• I had no y-axis legend.

I will now present an SQL query which allows for pluggable queries, which creates self, auto scaling graphs, along with y-axis scales.

Using deeply nested subqueries, we will evolve a simple SELECT query into an elaborate graph. I will present the many steps required, followed by explanations and sample results. But in the end – the steps are unimportant. I’ll present a generic query, into which your own SELECT can be embedded, and which will provide you with the graph.

We’ll use the same example, found in graph.sql.

Continue reading » “Generic, auto scaling, scaled SQL graphs”

We all love graphs. We all love SQL hacks. We all know the SQL hack which displays a character-based graph (example follows for those unfamiliar).

But we all love horizontal graphs, not vertical ones. We are used to the X axis being horizontal, Y being vertical. Not vice versa.

In this post I’ll present a SQL hack which rotates a vertical graph to horizontal. In fact, the technique shown will rotate any ‘textual image’; but graphs are a nice example.

A vertical graph example

What’s prettier than a sinus curve? I have prepared a simple table that will serve nicely, and can be found in graph_tables.sql.

Continue reading » “Rotating SQL graphs horizontally”