MySQL is the Most Popular Database Software when it comes to Websites. All Popular Content Management Systems work with MySQL like WordPress, vBulletin, Drupal, etc. But, you are probably reading this post because you are designing your own database wish to get a better understanding of the Number data types of MySQL, especially their size/capacity.
TINYINT – It Can Hold values from -128 to 127. Or 0 to 255 for Unsigned.
SMALLINT -It can Hold values -32768 to 32767 or 0 to 65535 UNSIGNED. This is most commonly used field for most websites.
MEDIUMINT – It can Hold values from -8388608 to 8388607 or 0 to 16777215 UNSIGNED.
INT – It can hold Values from -2147483648 to 2147483647 or 0 to 4294967295 UNSIGNED.
BIGINT – -9223372036854775808 to 9223372036854775807 normal. 0 to 18446744073709551615.
What to store a Bigger Integer? I don’t think MySQL provides anything Larger than BIGINT which can store values upto 264, which is a huge Number indeed. To Store Larger Values you can store them as Varchar, but won’t be able to process them like Integers.
Do you wish to store only a 4 Digit Number? To do so you can declare the data-type for any field as SMALLINT(4). All the above types take a parameter (size), which specifies the No. of Digits to be stores. But, you can not do something like TINYINT(8).
There are 3 Such Types in MySQL.
All these three Types, can be specified by the following Parameters (size, d). Where size is the total size of the String, and d represents precision. E.g To store a Number like 12345.678, you will set the Datatype to DOUBLE(8, 3) where 8 is the total no. of digits excluding the decimal point, and 3 is the no. of digits to follow the decimal.
FLOAT and DOUBLE, both represent floating point numbers. A FLOAT is for single-precision, while a DOUBLE is for double-precision numbers. A precision from 0 to 23 results in a 4-byte single-precision FLOAT column. A precision from 24 to 53 results in an 8-byte double-precision DOUBLE column. FLOAT is accurate to approximately 7 decimal places, and DOUBLE upto 14.
Decimal’s declaration and functioning is similar to Double. But there is one big difference between floating point values and decimal (numeric) values. We use DECIMAL data type to store exact numeric values, where we do not want precision but exact and accurate values. A Decimal type can store a Maximum of 65 Digits, with 30 digits after decimal point.
For those who did not understand, let me explain with an Example. Create 2 Columns with Types Double and Decimal and Store value 1.95 in both of them. If you print each column as Integer then you will see than Double Column has printed 1, while Decimal column printed 2.
Generally, Float values are good for scientific Calculations, but should not be used for Financial/Monetary Values. For Business Oriented Math, always use Decimal.