Describes the built-in functions available in Postgres.
Many data types have functions available for conversion to other related types. In addition, there are some type-specific functions. Some functions are also available through operators and may be documented as operators only.
"SQL functions" are constructs defined by the SQL92 standard which have function-like syntax but which can not be implemented as simple functions.
Table 4-1. SQL Functions
|COALESCE(list)||non-NULL||return first non-NULL value in list||COALESCE(r"le>, c2 + 5, 0)|
|IFNULL(input,non-NULL substitute)||non-NULL||return second argument if first is NULL||IFNULL(c1, 'N/A')|
|CASE WHEN expr THEN expr [...] ELSE expr END||expr||return expression for first true clause||CASE WHEN c1 = 1 THEN 'match' ELSE 'no match' END|