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.

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.

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.