Databases and SQL

Databases are a convenient way to store large quantities of information, and to cross reference different types of information. The SDSS provides a database with many of the derived quantities from the different SDSS surveys, and provides some tools to make accessing these databases fairly easy.

For SDSS, the main database is the Catalog Archive Server (CAS), which compiles derived quantities from the SDSS data (not images or spectra, but quantities that are derived from them: for example, ....?

  • More advanced queries can extract information from multiple tables, joining them on specified conditions; this is where the power of a relational database really comes in Accessing the CAS database: Practice: