basic question: decimal, single, double

[guy]

when i input 3.1234567890123456789,
single data type: 3.123457
double data type: 3.12345678901235
decimal data type: 3

does it mean only single and double data type can show decimal point?

thank you!

 

[guy]

i mean...what's the difference between the number field size property:
single, double, decimal?

 

[Douglas J. Steele]

Did you try looking in the Help file?

Single (single-precision floating-point) is 4 bytes in size and can hold
negative values between -3.402823E38 and -1.401298E-45, positive values
between 1.401298E-45 and 3.402823E38 or 0

Double (double-precision floating-point) is 8 bytes in size and can hold
negative values between -1.79769313486232E308 and -4.94065645841247E-324,
positive values between 4.94065645841247E-324 and 1.79769313486232E308 or 0

Decimal is 14 bytes is size and can hold values
+/-79,228,162,514,264,337,593,543,950,335 with no decimal point; or
+/-7.9228162514264337593543950335 with 28 places to the right of the
decimal. The smallest non-zero number it can hold is
+/-0.0000000000000000000000000001

There's also Currency (scaled integer) with is 8 bytes in size, and can hold
values between -922,337,203,685,477.5808 and 922,337,203,685,477.5807

 

[guy]

thank you for your reply.
i have checked the MS ACCESS help and a number of websites...i found all
these answers...

but the problem is....
when i input 3.1415926 in a number field (field size is decimal), ACCESS
automatically changed it to integer 3 and no decimal can be displayed...
why?

sorry, i am a computer idiot only...

 

[Van T. Dinh]

You need to set the Scale of the Decimal Field to 7 (for 7 decimal places)
instead of the default 0.

 

[guy]

thank you!

You need to set the Scale of the Decimal Field to 7 (for 7 decimal places)
instead of the default 0.

 

[onedaywhen]

Double (double-precision floating-point) is 8 bytes in size and can hold
negative values between -1.79769313486232E308 and -4.94065645841247E-324,
positive values between 4.94065645841247E-324 and 1.79769313486232E308 or 0

Decimal is 14 bytes is size and can hold values
+/-79,228,162,514,264,337,593,543,950,335 with no decimal point; or
+/-7.9228162514264337593543950335 with 28 places to the right of the
decimal. The smallest non-zero number it can hold is
+/-0.0000000000000000000000000001

The key to their differences is their accuracy. For their respective
ranges (stated above), the DECIMAL type can differentiate between *all*
values (i.e. is 100% accurate), whereas FLOAT (Double) uses
approximations and therefore is not always able to accurately
differentiate between close values. To test:

SELECT 0.12345678901234567 AS decimal_value_1,
decimal_value_1 + 0.00000000000000001 AS decimal_value_2,
CBOOL(decimal_value_1 = decimal_value_2) AS decimal_comparision,
CBOOL(CDBL(decimal_value_1) = CDBL(decimal_value_2)) AS
double_float_comparison;

or more simply

SELECT 0.12345678901234567 = CDBL(0.12345678901234567)

returns FALSE

There's also Currency (scaled integer) with is 8 bytes in size, and can hold
values between -922,337,203,685,477.5808 and 922,337,203,685,477.5807

FWIW DECIMAL is also a scaled integer type.

Jamie.

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