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 5-1. SQL Functions
|COALESCE(list)||non-NULL||return first non-NULL value in list||COALESCE(rle, c2 + 5, 0)|
|NULLIF(input,value)||input or NULL||return NULL if input = value, else input||NULLIF(c1, 'N/A')|
|CASE WHEN expr THEN expr [...] ELSE expr END||expr||return expression for first true WHEN clause||CASE WHEN c1 = 1 THEN 'match' ELSE 'no match' END|
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