In the previous section, we have seen how our existing table can be modified in order to add more fields to it, which can make our data even more valuable. Well, we are now ready to develop our first query. We will get the basic information about it first using the standard function of PostgreSQL, then we will be adding complexities to our queries. It's very important to fully understand and dominate the grouping and filtering of SQL before we can apply the spatial functions. For this reason, we must refresh all these skills first. We will see a set of practical exercises that will help us to get basic information about the data stored in our data tables. The data tables in our databases aren't related to each other, so you can work with each one separately.

We will work with the tbl_buildings table first. Let's check how many registers from London we have stored in our table; to do this, we will run the following query:

SELECT COUNT(*) FROM tbl_buildings WHERE town='London...