# 38. Triggers This chapter provides general information about writing trigger functions. Trigger functions can be written in most of the available procedural languages, including PL/pgSQL ([Chapter 42](https://www.postgresql.org/docs/13/plpgsql.html)), PL/Tcl ([Chapter 43](https://www.postgresql.org/docs/13/pltcl.html)), PL/Perl ([Chapter 44](https://www.postgresql.org/docs/13/plperl.html)), and PL/Python ([Chapter 45](https://www.postgresql.org/docs/13/plpython.html)). After reading this chapter, you should consult the chapter for your favorite procedural language to find out the language-specific details of writing a trigger in it. It is also possible to write a trigger function in C, although most people find it easier to use one of the procedural languages. It is not currently possible to write a trigger function in the plain SQL function language. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.postgresql.tw/14/server-programming/triggers.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.