It is recommended to not use the NUMERIC type, if precision is not required as the calculation on NUMERIC values is slower than integers, floats, and double precision.Ĭreate a new table named products with the below commands: CREATE TABLE IF NOT EXISTS products ( The NUMERIC and DECIMAL types are equivalent in PostgreSQL and upto the SQL standard. If you eliminate both precision and scale, there is no limit to the precision or the scale and the syntax will be as below: Syntax: NUMERIC It is allowed to have a zero or positive scale, as the syntax defined below for a NUMERIC column with the scale of zero: Syntax: NUMERIC(precision) The NUMERIC value can have up to 131, 072 digits before the decimal point of 16, 383 digits after the decimal point. Scale: Number of digits in terms of a fraction.
#POSTGRESQL ROUND MANUAL#
The pg_catalog functions are the default ones, see manual of build-in math functions. Pg_catalog | round | numeric | numeric, int Pg_catalog | round | double precision | double precision Myschema | round | numeric | double precision, int Myschema | round | double precision | double precision, text, int PS: checking \df round after overloadings, will show something like, Schema | Name | Result data type | Argument data types SELECT round(2.8+1/3.,'dec'::text) - need to cast string? pg bug complete!ĮLSE 'NaN'::float - like an error message To preserve the first commom-usage overload, we can return a FLOAT type when a TEXT parameter is offered, CREATE FUNCTION ROUND(float, text, int DEFAULT 0) Now your instruction will works fine, try (after function creation) SELECT round(1/3.,4) - 0.3333 numericīut it returns a NUMERIC type. You can overload the ROUND function with, CREATE FUNCTION ROUND(float,int) RETURNS NUMERIC AS $$
PS: another point about rounding is accuracy, check answer.
There are a lack of overloads in some PostgreSQL functions, why (?): I think "it is a lack" (!), but and the PostgreSQL team agree about "pg's historic rationale". Try also the old syntax for casting, SELECT ROUND(AVG(some_column)::numeric,2) The FM prefix tells to_char that you don't want any padding with leading spaces. To_char will round numbers for you as part of formatting. Use to_char (see: data type formatting functions in the manual), which lets you specify a format and gives you a text result that isn't affected by whatever weirdness your client language might do with numeric values. If you're formatting for display to the user, don't use round. Just append ::numeric for the shorthand cast, like round(val::numeric,2). You must cast the value to be rounded to numeric to use the two-argument form of round. You can see that PostgreSQL is expanding it in the output). (In the above, note that float8 is just a shorthand alias for double precision. Regress=> SELECT round( CAST(float8 '3.1415927' as numeric), 2) Pg_catalog | round | numeric | numeric, integer | normal Pg_catalog | round | numeric | numeric | normal Pg_catalog | round | double precision | double precision | normal Pg_catalog | dround | double precision | double precision | normal Schema | Name | Result data type | Argument data types | Type regress=> SELECT round( float8 '3.1415927', 2 ) ĮRROR: function round(double precision, integer) does not exist For reasons Sherrill 'Cat Recall' explains in the comments, the version of round that takes a precision is only available for numeric.
PostgreSQL does not define round(double precision, integer).
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