Structured Query Language – SQL
Locating Objects in a Database
When astronomers want to find an object in the sky with a telescope, they can simply look through the eyepiece and scan around, or if they know where the object is relative to a brighter object, they can star hop to the location. With the help of some additional technology on their telescopes, they can use the RA and Dec coordinates of the object to point to a precise location. But what do astronomers do when the images (and all the measurements that have been taken using those images) are stored in a computer database? For this task, we need a way to talk to the database and ask it to search for and return the information we need. This is the job of SQL or structured query language.
Decisions about how to design a database are very important. Before the Sloan Digital Sky Survey began capturing light from distant stars and galaxies in 1998, software engineers had to make decisions about how the data from the survey would be organized. They organized the SDSS database into tables, each of which contains columns of related information. An SQL query is a set of instructions that accesses this information. Let’s look at an example.