Extras zeroes getting appended during round to two decimal point in postgres - sql

I am writing a postgres procedure. In that I want to round a floating point number to two decimal point and then insert that into a table. I have written the below code.
vara float8;
SELECT round( float8 '3.1415927', 2 ) into vara;
insert into dummyTable(columnA)values(vara).
I want the columnA to contain the value 3.14. However the value which is getting inserted is 3.1400.
The data type of columnA is float8 with precision and scale 17.


There is only one function round with two arguments, and that takes numeric as argument:
test=> \df round
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+-------+------------------+---------------------+------
pg_catalog | round | double precision | double precision | func
pg_catalog | round | numeric | numeric | func
pg_catalog | round | numeric | numeric, integer | func
(3 rows)
So what happens is that your float8 is converted to numeric (without scale), and the result is of the same type. This will not produce trailing zeros:
test=> SELECT round(3.14159265, 2);
round
-------
3.14
(1 row)
But if you store the result in a float8 column, you may get rounding errors:
test=> SET extra_float_digits = 3;
SET
test=> SELECT round(3.14159265, 2)::float8;
round
---------------------
3.14000000000000012
(1 row)
My recommendation is to use numeric(10,2) or something similar as the data type of the table column, then the rounding will happen automatically, and the value can never have more than two decimal places.

Related

Postgres: why do I need to quote column name in max()? [duplicate]

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So I encountered the following behaviour which surprised me. I first thought DateTime might be a postgres data type but what about BidOpen? Then there is the funny thing with the case of the column name in the error message. I almost feel this has to do with unquoted names being case insensitive. Why do I need to surround the column name in quotes for the query to work?
mydatabase=# select max("DateTime") from fx.candle;
max
---------------------
2019-04-26 20:59:00
(1 row)
mydatabase=# select max(DateTime) from fx.candle;
ERROR: column "datetime" does not exist
LINE 1: select max(DateTime) from fx.candle;
^
HINT: Perhaps you meant to reference the column "candle.DateTime".
mydatabase=# select max(BidOpen) from fx.candle;
ERROR: column "bidopen" does not exist
LINE 1: select max(BidOpen) from fx.candle;
^
HINT: Perhaps you meant to reference the column "candle.BidOpen".
mydatabase=# select max("BidOpen") from fx.candle;
max
---------
125.816
(1 row)
The schema looks like this:
mydatabase=# \d fx.candle;
Table "fx.candle"
Column | Type | Modifiers
-----------+-----------------------------+-----------------------------------------------------------------
id | integer | not null default nextval('fx.candle_id_seq'::regclass)
DateTime | timestamp without time zone |
BidOpen | double precision | not null
BidHigh | double precision | not null
BidLow | double precision | not null
BidClose | double precision | not null
AskOpen | double precision | not null
AskHigh | double precision | not null
AskLow | double precision | not null
AskClose | double precision | not null
symbol_id | integer |
Indexes:
"candle_pkey" PRIMARY KEY, btree (id)
Foreign-key constraints:
"candle_symbol_id_fkey" FOREIGN KEY (symbol_id) REFERENCES fx.symbol(id)

My understanding is that Postgres is not case sensitive regarding column and table names unless you actually create them using double quotes in the beginning. If that be the case, then you would need to forever refer to them using double quotes, to ensure that the proper case literal is being used.
So, to avoid your current situation, you should also avoid creating column/table names in a case sensitive manner.
Your create table should look something like this:
create table fx.candle (
id integer not null default nextval('fx.candle_id_seq'::regclass),
...
datetime timestamp without time zone -- NO quotes here; important!
...
)

Rounding SUM (Float ) to one Decimal in PostGreSQL [duplicate]

I am using PostgreSQL via the Ruby gem 'sequel'.
I'm trying to round to two decimal places.
Here's my code:
SELECT ROUND(AVG(some_column),2)
FROM table
I get the following error:
PG::Error: ERROR: function round(double precision, integer) does
not exist (Sequel::DatabaseError)
I get no error when I run the following code:
SELECT ROUND(AVG(some_column))
FROM table
Does anyone know what I am doing wrong?

PostgreSQL does not define round(double precision, integer). For reasons #Mike Sherrill 'Cat Recall' explains in the comments, the version of round that takes a precision is only available for numeric.
regress=> SELECT round( float8 '3.1415927', 2 );
ERROR: function round(double precision, integer) does not exist
regress=> \df *round*
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+--------+------------------+---------------------+--------
pg_catalog | dround | double precision | double precision | normal
pg_catalog | round | double precision | double precision | normal
pg_catalog | round | numeric | numeric | normal
pg_catalog | round | numeric | numeric, integer | normal
(4 rows)
regress=> SELECT round( CAST(float8 '3.1415927' as numeric), 2);
round
-------
3.14
(1 row)
(In the above, note that float8 is just a shorthand alias for double precision. You can see that PostgreSQL is expanding it in the output).
You must cast the value to be rounded to numeric to use the two-argument form of round. Just append ::numeric for the shorthand cast, like round(val::numeric,2).
If you're formatting for display to the user, don't use round. 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. For example:
regress=> SELECT to_char(float8 '3.1415927', 'FM999999999.00');
to_char
---------------
3.14
(1 row)
to_char will round numbers for you as part of formatting. The FM prefix tells to_char that you don't want any padding with leading spaces.

        ((this is a Wiki! please edit to enhance!))
Try also the old syntax for casting,
SELECT ROUND( AVG(some_column)::numeric, 2 ) FROM table;
works with any version of PostgreSQL. ...But, as definitive solution, you can overload the ROUND function.
Overloading as casting strategy
CREATE FUNCTION ROUND(float,int) RETURNS NUMERIC AS $f$
SELECT ROUND( CAST($1 AS numeric), $2 )
$f$ language SQL IMMUTABLE;
Now your instruction will works fine, try this complete comparison:
SELECT trunc(n,3), round(n,3) n_round, round(f,3) f_round,
pg_typeof(n) n_type, pg_typeof(f) f_type, pg_typeof(round(f,3)) f_round_type
FROM (SELECT 2.0/3.0, 2/3::float) t(n,f);
trunc
n_round
f_round
n_type
f_type
f_round_type
0.666
0.667
0.667
numeric
double precision
numeric
The ROUND(float,int) function is f_round, it returns a (decimal) NUMERIC datatype, that is fine for some applications: problem solved!
In another applications we need a float also as result. An alternative is to use round(f,3)::float or to create a round_tofloat() function.
Other alternative, overloading ROUND function again, and using all range of accuracy-precision of a floating point number, is to return a float when the accuracy is defined (see IanKenney's answer),
CREATE FUNCTION ROUND(
input float, -- the input number
accuracy float -- accuracy, the "counting unit"
) RETURNS float AS $f$
SELECT ROUND($1/accuracy)*accuracy
$f$ language SQL IMMUTABLE;
Try
SELECT round(21.04, 0.05); -- 21.05 float!
SELECT round(21.04, 5::float); -- 20
SELECT round(1/3., 0.0001); -- 0.3333
SELECT round(2.8+1/3., 0.5); -- 3.15
SELECT round(pi(), 0.0001); -- 3.1416
PS: the command \df round, on psql after overloadings, will show something like this table
Schema | Name | Result | Argument
------------+-------+---------+------------------
myschema | round | numeric | float, int
myschema | round | float | float, float
pg_catalog | round | float | float
pg_catalog | round | numeric | numeric
pg_catalog | round | numeric | numeric, int
where float is synonymous of double precision and myschema is public when you not use a schema. The pg_catalog functions are the default ones, see at Guide the build-in math functions.
Rounding and formating
The to_char function apply internally the round procedure, so, when your aim is only to show a final result in the terminal, you can use the FM modifier as a prefix to a numeric format pattern:
SELECT round(x::numeric,2), trunc(x::numeric,2), to_char(x, 'FM99.99')
FROM (SELECT 2.0/3) t(x);
round
trunc
to_char
0.67
0.66
.67
NOTES
Cause of the problem
There are a lack of overloads in some PostgreSQL functions, why (???): I think "it is a lack" (!), but #CraigRinger, #Catcall and the PostgreSQL team agree about "pg's historic rationale".
Note about performance and reuse
The build-in functions, such as ROUND of the pg_catalog, can be overloaded with no performance loss, when compared to direct cast encoding. Two precautions must be taken when implementing user-defined cast functions for high performance:
The IMMUTABLE clause is very important for code snippets like this, because, as said in the Guide: "allows the optimizer to pre-evaluate the function when a query calls it with constant arguments"
PLpgSQL is the preferred language, except for "pure SQL". For JIT optimizations (and sometimes for parallelism) language SQL can obtain better optimizations. Is something like copy/paste small piece of code instead of use a function call.
Conclusion: the above ROUND(float,int) function, after optimizations, is so fast than #CraigRinger's answer; it will compile to (exactly) the same internal representation. So, although it is not standard for PostgreSQL, it can be standard for your projects, by a centralized and reusable "library of snippets", like pg_pubLib.
Round to the nth bit or other numeric representation
Some people argue that it doesn't make sense for PostgreSQL to round a number of float datatype, because float is a binary representation, it requires rounding the number of bits or its hexadecimal representation.
Well, let's solve the problem, adding an exotic suggestion... The aim here is to return a float type in another overloaded function,   ROUND(float, text, int) RETURNS float The text is to offer a choice between
'dec' for "decimal representation",
'bin' for "binary" representation and
'hex' for hexadecimal representation.
So, in different representations we have a different interpretation about the number of digits to be rounded. Rounding a number x with an approximate shorter value, with less "fractionary digits" (tham its original d digits), will be shorter when d is couting binary digits instead decimal or hexadecimal.
It is not easy without C++, using "pure SQL", but this code snippets will illustrate and can be used as workaround:
-- Looking for a round_bin() function! this is only a workaround:
CREATE FUNCTION trunc_bin(x bigint, t int) RETURNS bigint AS $f$
SELECT ((x::bit(64) >> t) << t)::bigint;
$f$ language SQL IMMUTABLE;
CREATE FUNCTION ROUND(
x float,
xtype text, -- 'bin', 'dec' or 'hex'
xdigits int DEFAULT 0
)
RETURNS FLOAT AS $f$
SELECT CASE
WHEN xtype NOT IN ('dec','bin','hex') THEN 'NaN'::float
WHEN xdigits=0 THEN ROUND(x)
WHEN xtype='dec' THEN ROUND(x::numeric,xdigits)
ELSE (s1 ||'.'|| s2)::float
END
FROM (
SELECT s1,
lpad(
trunc_bin( s2::bigint, CASE WHEN xd<bin_bits THEN bin_bits - xd ELSE 0 END )::text,
l2,
'0'
) AS s2
FROM (
SELECT *,
(floor( log(2,s2::numeric) ) +1)::int AS bin_bits, -- most significant bit position
CASE WHEN xtype='hex' THEN xdigits*4 ELSE xdigits END AS xd
FROM (
SELECT s[1] AS s1, s[2] AS s2, length(s[2]) AS l2
FROM (SELECT regexp_split_to_array(x::text,'\.')) t1a(s)
) t1b
) t1c
) t2
$f$ language SQL IMMUTABLE;
Try
SELECT round(1/3.,'dec',4); -- 0.3333 float!
SELECT round(2.8+1/3.,'dec',1); -- 3.1 float!
SELECT round(2.8+1/3.,'dec'); -- ERROR, need to cast string
SELECT round(2.8+1/3.,'dec'::text); -- 3 float
SELECT round(2.8+1/3.,'dec',0); -- 3 float
SELECT round(2.8+1/3.,'hex',0); -- 3 float (no change)
SELECT round(2.8+1/3.,'hex',1); -- 3.1266
SELECT round(2.8+1/3.,'hex',3); -- 3.13331578486784
SELECT round(2.8+1/3.,'bin',1); -- 3.1125899906842625
SELECT round(2.8+1/3.,'bin',6); -- 3.1301821767286784
SELECT round(2.8+1/3.,'bin',12); -- 3.13331578486784
And \df round have also:
Schema | Name | Result | Argument
------------+-------+---------+---------------
myschema | round | float | x float, xtype text, xdigits int DEFAULT 0

Try with this:
SELECT to_char (2/3::float, 'FM999999990.00');
-- RESULT: 0.67
Or simply:
SELECT round (2/3::DECIMAL, 2)::TEXT
-- RESULT: 0.67

you can use the function below
SELECT TRUNC(14.568,2);
the result will show :
14.56
you can also cast your variable to the desire type :
SELECT TRUNC(YOUR_VAR::numeric,2)

SELECT ROUND(SUM(amount)::numeric, 2) AS total_amount
FROM transactions
Gives: 200234.08

Try casting your column to a numeric like:
SELECT ROUND(cast(some_column as numeric),2) FROM table

According to Bryan's response you can do this to limit decimals in a query. I convert from km/h to m/s and display it in dygraphs but when I did it in dygraphs it looked weird. Looks fine when doing the calculation in the query instead. This is on postgresql 9.5.1.
select date,(wind_speed/3.6)::numeric(7,1) from readings;

Error:function round(double precision, integer) does not exist
Solution: You need to addtype cast then it will work
Ex: round(extract(second from job_end_time_t)::integer,0)

Appropriate values for -Infinity & Infinity in Postgres

In one of the cases we have to feed values for +infinity & -infinity in Postgres DB?
What should be appropriate value that should be considered.
If there is not 1, then please suggest the best suited.
Thank You

You can actually use +infinity and -infinity for FLOAT4 and FLOAT8 (i.e. float and double precision) data types, and for timestamps.
regress=> SELECT FLOAT8 '+infinity', FLOAT8 '-infinity';
float8 | float8
----------+-----------
Infinity | -Infinity
(1 row)
For other types, either use a separate column, use the minimum/maximum values for the type, or (where logically appropriate) use null.

You can insert the string 'infinity' or '-infinity' into a numeric/float/real/double precision column types. However, this will be out of range error for integer/bigint/smallint.
'+infinity' and 'infinity' and 'Infinity' are equivalent
'-infinity' and '-Infinity' are equivalent
Some example that work ✅ :
INSERT INTO table
(real_column)
VALUES ('-Infinity'::float);
or even
INSERT INTO table
(numeric_column)
VALUES ('infinity'::numeric);
or
INSERT INTO table
(float_column)
VALUES ('+infinity');

add another column name "infinite", 1 means +infinity, -1 means -infinity
when you are checking numbers, check the column first.
this will save you a lot of time thinking about magic numbers or other stuff.

How to round an average to 2 decimal places in PostgreSQL?

I am using PostgreSQL via the Ruby gem 'sequel'.
I'm trying to round to two decimal places.
Here's my code:
SELECT ROUND(AVG(some_column),2)
FROM table
I get the following error:
PG::Error: ERROR: function round(double precision, integer) does
not exist (Sequel::DatabaseError)
I get no error when I run the following code:
SELECT ROUND(AVG(some_column))
FROM table
Does anyone know what I am doing wrong?

PostgreSQL does not define round(double precision, integer). For reasons #Mike Sherrill 'Cat Recall' explains in the comments, the version of round that takes a precision is only available for numeric.
regress=> SELECT round( float8 '3.1415927', 2 );
ERROR: function round(double precision, integer) does not exist
regress=> \df *round*
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+--------+------------------+---------------------+--------
pg_catalog | dround | double precision | double precision | normal
pg_catalog | round | double precision | double precision | normal
pg_catalog | round | numeric | numeric | normal
pg_catalog | round | numeric | numeric, integer | normal
(4 rows)
regress=> SELECT round( CAST(float8 '3.1415927' as numeric), 2);
round
-------
3.14
(1 row)
(In the above, note that float8 is just a shorthand alias for double precision. You can see that PostgreSQL is expanding it in the output).
You must cast the value to be rounded to numeric to use the two-argument form of round. Just append ::numeric for the shorthand cast, like round(val::numeric,2).
If you're formatting for display to the user, don't use round. 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. For example:
regress=> SELECT to_char(float8 '3.1415927', 'FM999999999.00');
to_char
---------------
3.14
(1 row)
to_char will round numbers for you as part of formatting. The FM prefix tells to_char that you don't want any padding with leading spaces.

        ((this is a Wiki! please edit to enhance!))
Try also the old syntax for casting,
SELECT ROUND( AVG(some_column)::numeric, 2 ) FROM table;
works with any version of PostgreSQL. ...But, as definitive solution, you can overload the ROUND function.
Overloading as casting strategy
CREATE FUNCTION ROUND(float,int) RETURNS NUMERIC AS $f$
SELECT ROUND( CAST($1 AS numeric), $2 )
$f$ language SQL IMMUTABLE;
Now your instruction will works fine, try this complete comparison:
SELECT trunc(n,3), round(n,3) n_round, round(f,3) f_round,
pg_typeof(n) n_type, pg_typeof(f) f_type, pg_typeof(round(f,3)) f_round_type
FROM (SELECT 2.0/3.0, 2/3::float) t(n,f);
trunc
n_round
f_round
n_type
f_type
f_round_type
0.666
0.667
0.667
numeric
double precision
numeric
The ROUND(float,int) function is f_round, it returns a (decimal) NUMERIC datatype, that is fine for some applications: problem solved!
In another applications we need a float also as result. An alternative is to use round(f,3)::float or to create a round_tofloat() function.
Other alternative, overloading ROUND function again, and using all range of accuracy-precision of a floating point number, is to return a float when the accuracy is defined (see IanKenney's answer),
CREATE FUNCTION ROUND(
input float, -- the input number
accuracy float -- accuracy, the "counting unit"
) RETURNS float AS $f$
SELECT ROUND($1/accuracy)*accuracy
$f$ language SQL IMMUTABLE;
Try
SELECT round(21.04, 0.05); -- 21.05 float!
SELECT round(21.04, 5::float); -- 20
SELECT round(1/3., 0.0001); -- 0.3333
SELECT round(2.8+1/3., 0.5); -- 3.15
SELECT round(pi(), 0.0001); -- 3.1416
PS: the command \df round, on psql after overloadings, will show something like this table
Schema | Name | Result | Argument
------------+-------+---------+------------------
myschema | round | numeric | float, int
myschema | round | float | float, float
pg_catalog | round | float | float
pg_catalog | round | numeric | numeric
pg_catalog | round | numeric | numeric, int
where float is synonymous of double precision and myschema is public when you not use a schema. The pg_catalog functions are the default ones, see at Guide the build-in math functions.
Rounding and formating
The to_char function apply internally the round procedure, so, when your aim is only to show a final result in the terminal, you can use the FM modifier as a prefix to a numeric format pattern:
SELECT round(x::numeric,2), trunc(x::numeric,2), to_char(x, 'FM99.99')
FROM (SELECT 2.0/3) t(x);
round
trunc
to_char
0.67
0.66
.67
NOTES
Cause of the problem
There are a lack of overloads in some PostgreSQL functions, why (???): I think "it is a lack" (!), but #CraigRinger, #Catcall and the PostgreSQL team agree about "pg's historic rationale".
Note about performance and reuse
The build-in functions, such as ROUND of the pg_catalog, can be overloaded with no performance loss, when compared to direct cast encoding. Two precautions must be taken when implementing user-defined cast functions for high performance:
The IMMUTABLE clause is very important for code snippets like this, because, as said in the Guide: "allows the optimizer to pre-evaluate the function when a query calls it with constant arguments"
PLpgSQL is the preferred language, except for "pure SQL". For JIT optimizations (and sometimes for parallelism) language SQL can obtain better optimizations. Is something like copy/paste small piece of code instead of use a function call.
Conclusion: the above ROUND(float,int) function, after optimizations, is so fast than #CraigRinger's answer; it will compile to (exactly) the same internal representation. So, although it is not standard for PostgreSQL, it can be standard for your projects, by a centralized and reusable "library of snippets", like pg_pubLib.
Round to the nth bit or other numeric representation
Some people argue that it doesn't make sense for PostgreSQL to round a number of float datatype, because float is a binary representation, it requires rounding the number of bits or its hexadecimal representation.
Well, let's solve the problem, adding an exotic suggestion... The aim here is to return a float type in another overloaded function,   ROUND(float, text, int) RETURNS float The text is to offer a choice between
'dec' for "decimal representation",
'bin' for "binary" representation and
'hex' for hexadecimal representation.
So, in different representations we have a different interpretation about the number of digits to be rounded. Rounding a number x with an approximate shorter value, with less "fractionary digits" (tham its original d digits), will be shorter when d is couting binary digits instead decimal or hexadecimal.
It is not easy without C++, using "pure SQL", but this code snippets will illustrate and can be used as workaround:
-- Looking for a round_bin() function! this is only a workaround:
CREATE FUNCTION trunc_bin(x bigint, t int) RETURNS bigint AS $f$
SELECT ((x::bit(64) >> t) << t)::bigint;
$f$ language SQL IMMUTABLE;
CREATE FUNCTION ROUND(
x float,
xtype text, -- 'bin', 'dec' or 'hex'
xdigits int DEFAULT 0
)
RETURNS FLOAT AS $f$
SELECT CASE
WHEN xtype NOT IN ('dec','bin','hex') THEN 'NaN'::float
WHEN xdigits=0 THEN ROUND(x)
WHEN xtype='dec' THEN ROUND(x::numeric,xdigits)
ELSE (s1 ||'.'|| s2)::float
END
FROM (
SELECT s1,
lpad(
trunc_bin( s2::bigint, CASE WHEN xd<bin_bits THEN bin_bits - xd ELSE 0 END )::text,
l2,
'0'
) AS s2
FROM (
SELECT *,
(floor( log(2,s2::numeric) ) +1)::int AS bin_bits, -- most significant bit position
CASE WHEN xtype='hex' THEN xdigits*4 ELSE xdigits END AS xd
FROM (
SELECT s[1] AS s1, s[2] AS s2, length(s[2]) AS l2
FROM (SELECT regexp_split_to_array(x::text,'\.')) t1a(s)
) t1b
) t1c
) t2
$f$ language SQL IMMUTABLE;
Try
SELECT round(1/3.,'dec',4); -- 0.3333 float!
SELECT round(2.8+1/3.,'dec',1); -- 3.1 float!
SELECT round(2.8+1/3.,'dec'); -- ERROR, need to cast string
SELECT round(2.8+1/3.,'dec'::text); -- 3 float
SELECT round(2.8+1/3.,'dec',0); -- 3 float
SELECT round(2.8+1/3.,'hex',0); -- 3 float (no change)
SELECT round(2.8+1/3.,'hex',1); -- 3.1266
SELECT round(2.8+1/3.,'hex',3); -- 3.13331578486784
SELECT round(2.8+1/3.,'bin',1); -- 3.1125899906842625
SELECT round(2.8+1/3.,'bin',6); -- 3.1301821767286784
SELECT round(2.8+1/3.,'bin',12); -- 3.13331578486784
And \df round have also:
Schema | Name | Result | Argument
------------+-------+---------+---------------
myschema | round | float | x float, xtype text, xdigits int DEFAULT 0

Try with this:
SELECT to_char (2/3::float, 'FM999999990.00');
-- RESULT: 0.67
Or simply:
SELECT round (2/3::DECIMAL, 2)::TEXT
-- RESULT: 0.67

you can use the function below
SELECT TRUNC(14.568,2);
the result will show :
14.56
you can also cast your variable to the desire type :
SELECT TRUNC(YOUR_VAR::numeric,2)

SELECT ROUND(SUM(amount)::numeric, 2) AS total_amount
FROM transactions
Gives: 200234.08

Try casting your column to a numeric like:
SELECT ROUND(cast(some_column as numeric),2) FROM table

According to Bryan's response you can do this to limit decimals in a query. I convert from km/h to m/s and display it in dygraphs but when I did it in dygraphs it looked weird. Looks fine when doing the calculation in the query instead. This is on postgresql 9.5.1.
select date,(wind_speed/3.6)::numeric(7,1) from readings;

Error:function round(double precision, integer) does not exist
Solution: You need to addtype cast then it will work
Ex: round(extract(second from job_end_time_t)::integer,0)

T-SQL Parameters

I have the following table in SQL Server 2000:
TABLE_NAME | COLUMN_NAME | TYPE_NAME | PRECISION | LENGTH | SCALE |
test TestID int 10 4 0
test TestDecimal decimal 18 20 2
test TestFloat float 15 8 NULL
test TestMoney money 19 21 4
My question is, if I wanted to created a stored procedure that takes 4 parameters based on my table fields, how do I do this. I have this solution:
CREATE PROCEDURE TestProc ( #TestID int, #TestDecimal decimal, #TestFloat float, #TestMoney money )
AS
.....
.....
.....
GO
This works, except I think #TestDecimal loses its decimal portion, thus converting it into a whole number. Do I need to put #TestDecimal decimal(Precision,Scale) instead of just decimal? and if so, is there any other numeric datatypes that I need to specify this type of parameter encoding?

Yes, you need to specifc (18,2) for decimal/numeric
The same applies to float/real, (n)varchar, (n)char, (var)binary, datetime2 (missed any?)
A different precision, scale or length is in effect a different datatype and a conversion will occur.
Example question of why differenmt varchar lengths make different datatypes

Your parameter type must match the database column type. A database type is defined not only by its base type, but also by its actual length and precision, when it applies. TestDecimal id actualy DECIMAL(18,2) in your example.