Functions and Triggers

 Chapter  focused on client-side programming--programs that run on the user's computer and interact with the POSTGRESQL database. Server-side functions, sometimes called stored procedures , run inside the database server rather than in the client application.

Several good uses for server-side functions exist. For example, if a function is used by many applications, it can be embedded into the database server. With this approach, each application no longer needs a copy of the function. Whenever the function is needed, the client can simply call it. Unlike client-side functions, server-side functions can be called within SQL queries. Also, functions centrally installed in the server are easily modified. When a function is changed, all client applications immediately start using the new version.

Table  on page  lists many preinstalled server-side functions, like upper () and date_part (). This chapter shows how to create your own functions. It also covers special server-side functions called triggers, which are called automatically when a table is modified.  

 

• Functions
• SQL Functions
• PL/PGSQL Functions
• Triggers
• Summary