[SOLVED] Length/Values-What on earth is it?

[xstevex]

Hi,

 

I was instructed by someone to do some modifications to my database, now I can't get in contact with him to ask some more questions. What he said was:

 

"...First, you have to change the database rating to type Double, length 7 dec 6."

 

The "rating" is the name of the field. And I know "Double" is set in Type.

 

What I don't know is "length 7 dec 6" but I assume this refers to the Length/Values settings. If so would I type this in as "7.6"? I have no idea.

 

Please advise if you know what "length 7 dec 6" would mean.  ???

 

Steve

 

 

[fenway]

The length of decimals fields includes all sig-figs... so you need to "decide" how many to allocate to decimal places.

[xstevex]

Hi Fenway,

 

Thanks for your answer. So I would have the significant figures set to 7 and the decimals of those "sig-figs" would be 6. So seven figures total, of which six would be decimals. One integer and six decimals.

 

How do I tell this to MySql in the Length/Values area?

 

I'm guessing I write it in as "7,6"

 

Steve.

[revraz]

Yes

[xstevex]

Ok, thank you. I learnt something new today.

 

Steve

[revraz]

From this link:

 

http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html

 

 

MySQL allows a non-standard syntax: FLOAT(M,D) or REAL(M,D) or DOUBLE PRECISION(M,D). Here, “(M,D)” means than values can be stored with up to M digits in total, of which D digits may be after the decimal point. For example, a column defined as FLOAT(7,4) will look like -999.9999 when displayed. MySQL performs rounding when storing values, so if you insert 999.00009 into a FLOAT(7,4) column, the approximate result is 999.0001. 

[xstevex]

Thanks Revraz,

 

This will be useful to know in the future.