To include a template in this category, add <noinclude>[[Category:Database templates]]</noinclude> to the end of the template code, making sure it starts on the same line as the last character of the code.
Database templates are templates which are used to change the value of a parameter from one value to another, in which the template uses the parameter to change it from its contents to something else, e.g. the template is a kind of database lookup. They are used to do table lookups, value substitutions, and transformation of data. For example, a parameter might convert the two-letter state abbreviation to its full name, or change the two-digit FIPS code for a state to its abbreviation, show the full name for the abbreviation of a Swiss Canton, show the frequency range for a television channel number, etc.