----- Original Message -----
From: "Keith Stokes" <[EMAIL PROTECTED]>
To: "mysql" <[EMAIL PROTECTED]>
Sent: Thursday, April 19, 2001 22:15
Subject: PROBLEMS UNDERSTANDING FLOAT/DOUBLE COLUMN TYPES
> PROBLEMS UNDERSTANDING FLOAT/DOUBLE COLUMN TYPES
>
> First could you clarify the contradictions from the following extracts of
> the manual.
>
>
> 7.3 Column types
>
> The column types supported by MySQL are listed below. The following code
> letters are used in the descriptions:
>
> M Indicates the maximum display size. The maximum legal display size is
> 255.
> D Applies to floating-point types and indicates the number of digits
> following the decimal point. The maximum possible value is 30, but should
> be no greater than M-2.
>
> Square brackets (`[' and `]') indicate parts of type specifiers that are
> optional.
>
> Note that if you specify ZEROFILL for a column, MySQL will automatically
> add the UNSIGNED attribute to the column.
>
>
> FLOAT[(M,D)] [ZEROFILL]
> A small (single-precision) floating-point number. Cannot be
> unsigned. Allowable values are -3.402823466E+38 to -1.175494351E-38, 0 and
> 1.175494351E-38 to 3.402823466E+38. The M is the display width and D is
the
> number of decimals. FLOAT without an argument or with an argument of
<=
> 24 stands for a single-precision floating point number.
> DOUBLE[(M,D)] [ZEROFILL]
> A normal-size (double-precision) floating-point number. Cannot be
> unsigned. Allowable values are -1.7976931348623157E+308 to
> -2.2250738585072014E-308, 0 and 2.2250738585072014E-308 to
> 1.7976931348623157E+308. The M is the display width and D is the number of
> decimals. DOUBLE without an argument or FLOAT(X) where 25 <= X <= 53
> stands for a double-precision floating point number.
>
> 7.7 CREATE TABLE syntax
>
> DOUBLE[(length,decimals)] [UNSIGNED] [ZEROFILL]
> FLOAT[(length,decimals)] [UNSIGNED] [ZEROFILL]
> DECIMAL(length,decimals) [UNSIGNED] [ZEROFILL]
> NUMERIC(length,decimals) [UNSIGNED] [ZEROFILL]
>
>
> As you can see from the above the FLOAT/DOUBLE columns cannot be unsigned
> or can they?.
I don't understand what you mean. Where does it say it CAN'T be unsigned?
To me, it is quite obvious that it can be.
> Second problem what is "Allowable values are -3.402823466E+38 to
> -1.175494351E-38, 0 and 1.175494351E-38 to 3.402823466E+38 "
> in real numbers I.E. how many digits?.
Again I do not understand what you are asking. You can, but it is
impractical, to write
-1.175494351E-38 as
-0.00000000000000000000000000000000000001175494351
Or do you mean the number of significant digits, which is described as M & D
at the start?
Or have I totally misunderstood you?
>
> Thanking you in advance
>
>
>
> Keith Stokes
>
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