Basic Syntax#
What is SQL? As described in Library Carpentry’s Introduction to SQL tutorial, “Structured Query Language, or SQL (sometimes pronounced ‘sequel’), is a powerful language used to interrogate and manipulate relational databases. It is not a general programming language that you can use to write an entire program.”
When working with relational database systems, we can use SQL to write queries. As described in Library Carpentry’s Introduction to SQL tutorial, “a query is a question or request for data. For example, “How many journals does our library subscribe to?” When we query a database, we can ask the same question using a common language called Structured Query Language or SQL in what is called a statement. Some of the most useful queries - the ones we are introducing in this first section - are used to return results from a table that match specific criteria.”
DB Browser Setup#
In the DB Browser program, select the Open Database icon. Open the .db file from the previous section.
Click the Execute SQL tab. The top text-box on the left-hand pane in the program (immediately below SQL 1) is where we will type SQL statements.
![](https://github.com/kwaldenphd/elements-of-computing/blob/main/book/images/ch4/fig6.jpg?raw=true")
Once we start adding SQL syntax, we can run all (or a selection) using the single arrow icon (left of the two arrows, immediate right of print).
We can use the other arrow (right of the two arrows) to run a single line.
Comments#
We can add single-line comments to our SQL statements using a double dash
--.-- this is my single-line comment