4. sql

Okay, we have a

Okay, we have a

Now what?

Suppose I need these two valuesEvery week

on new data

Don’t paste!

• Make repeatable

analyses (without

clicking)• Easily add data

Structured query language


• Developed at IBM


• Developed at IBM• Usually NOT considered

a programming language




• But a “domain specific language”




• But a “domain specific language”

• Aimed at analyzing and manipulating DATA


on new data

Where is

like ‘filter’

in Excel

But we need

temperature?

In Excel, we

did a lookup

Temperatur

e is here

To fix a bit (move

rows up)

This results in

Carthesian

product

This is called a ‘JOIN’

Very similar to

VLOOKUP

We have a

temperatur

e field now

We have the

filter

We still need to

show: Machine &

temperature

Benefit over Excel:

We can have

multiple such

queries

We have the

right data

We have the

right dataBut! We

need ‘pivot like’

summary on average

AVG of what?

Of everything?

Per machine?

Almost there!


on new data

Remember lecture

1?

• Make repeatable

analyses (without

clicking)• Easily add data

Can’t pick

field names now

We made an easily

repeatable

analysis!

Education