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I have a few values that come in from a server that need to be stored in my database. I'm not a MySQL expert, but I understand it well enough for basic input/output. Right now I am trying to determine the length I should be using when storing the following decimals.
tax_rate [DECIMAL ?,?]: value(0.014840000000)
units [DECIMAL ?,?]: value(1.00)
initial_charge [DECIMAL ?,?]: value(2.5110)
charge [DECIMAL ?,?]: value(2.8967)
link_tax [DECIMAL ?,?]: value(0.385652)
exempt [DECIMAL ?,?]: value(0.0000)
tax [DECIMAL ?,?]: value(0.042986)
base_price [DECIMAL ?,?]: value(41.8500)
I'm hoping someone could suggest the correct size I need to use for these values AS WELL explain why they chose the values. Or maybe link to an article that explains MySQL decimals in depth.
Any help would be appreciated.
Thank you!
-------Edit--------
After reading the MySQL docs, there is a very good explanation to determining the size of the decimal type. These are the sizes I have set for my use case:
tax_rate [DECIMAL 15,12]: value(0.014840000000) ? max(999.999999999999)
units [DECIMAL 6,2]: value(1.00) ? max(9999.99)
initial_charge [DECIMAL 9,4]: value(2.5110) ? max(99999.9999)
charge [DECIMAL 9,4]: value(2.8967) ? max(99999.9999)
link_tax [DECIMAL 9,6]: value(0.385652) ? max(999.999999)
exempt [DECIMAL 9,4]: value(0.0000) ? max(9999.9999)
tax [DECIMAL 10,6]: value(0.042986) ? max(999999.999999)
base_price [DECIMAL 10,4]: value(41.8500) ? max(999999.9999)
849
Range: The range of DECIMAL type is -10^38 +1 through 10^38 –1. The largest value is represented by DECIMAL(38, 0) . The most precise fractional value (between 0 and 1, or 0 and -1) is represented by DECIMAL(38, 38) , with 38 digits to the right of the decimal point.
It has a range of 1 to 65. D is the number of digits to the right of the decimal point (the scale).
In MySQL, the DECIMAL and NUMERIC data types store exact, fixed-point values. In MySQL, NUMERIC is implemented as a DECIMAL, so a NUMERIC and DECIMAL are the same data type. This data type is used when it is important to preserve the exact precision, such as storing money data.
The short answer is: No, it will hurt performance. The longer answer: VARCHAR fields are variable length, meaning, that the formatting of the database blocks cannot pre-account for the size of the data filling in there.
From MySQL:
The declaration syntax for a DECIMAL column is DECIMAL(M,D). The ranges of values for the arguments in MySQL 5.1 are as follows:
M is the maximum number of digits (the precision). It has a range of 1 to 65. (Older versions of MySQL permitted a range of 1 to 254.)
D is the number of digits to the right of the decimal point (the scale). It has a range of 0 to 30 and must be no larger than M.
Consider this number: 123456789.12345 here M is 14 and D is 5 then based on this principle you can set DECIMALS(M,D) for each column based on Their expected maximum values.
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