PostgreSQL 為內建的資料型別提供了大量的函數和運算子。使用者還可以定義自己的函數和運算子,如第 V 部分所述。psql 指令 \df 和 \do 可分別用於列出所有可用的函數和運算子。
The notation used throughout this chapter to describe the argument and result data types of a function or operator is like this:
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repeat ( text, integer ) → text
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which says that the function repeat takes one text and one integer argument and returns a result of type text. The right arrow is also used to indicate the result of an example, thus: