2 - SQL Introduction

Structured Query Language (SQL) is a standard language for accessing and manipulating databases. Databases are just a group of data tables. Below is an example of a table called "Degrees" that could be in a database.

Major	StartingMedianSalary	MidCareerMedianSalary
Accounting	46000.00	77100.00
Aerospace Engineering	57700.00	101000.00
Agriculture	42600.00	71900.00
Anthropology	36800.00	61500.00

We can then use SQL to "filter" the table. For example the following SQL statement..

SELECT Major, StartingMedianSalary FROM Degrees

would generate the following table.

Major	StartingMedianSalary
Accounting	46000.00
Aerospace Engineering	57700.00
Agriculture	42600.00
Anthropology	36800.00

We simply SELECT columns FROM a table. Above we selected the columns "Major" and "StartingMedianSalary" from the "Degrees" table.

We can also use * (a wild card) for the columns to get all the columns. So, SELECT * FROM Degrees will result in the full table.

Try It OUT

1 - Find the following Javascript in your code.js file.

viz.chart({
    sql:"SELECT * FROM Degrees",
    chartType:"Table",
    containerId:"chart2"
});

Notice how this code generates the table in your web view, where the table has a lot of columns (actually, all of them).

2 - Now change the SQL to the following to select only two columns.

SELECT Major, StartingMedianSalary FROM Degrees

Run your web app and notice how the table has changed.

3 - Now try the following SQL to get all the columns from a different table.

SELECT * FROM States

This gets a different table, "States", that can be found in our example database.

4 - Go to this Google Sheet to see the example database and notice how each sheet (tab) is a table with a unique name.

You will use SQL to get the right data from a database (Google Sheets file) for the charts you want to display. Next, let's look at producing the actual charts.