![]() There are also two extensions of the text types that result in a different behavior ENUM and SETwhich allow you to define a series of acceptable values when creating the table. Mostly these differ in size, but several allow for storing binary data instead of strings of characters. Range of 128 to 127 or 0 to 255 unsigned. (As of MySQL 5.0.3, the size of DECIMAL column is based upon a formula.) MySQL Numeric Types For FLOAT, DOUBLE, and DECIMAL, the Length argument is the maximum total number of digits and the Decimals argument dictates the number of that total to be found after the decimal point. Here are most of the available numeric column types for use with MySQL databases. After that it's a matter of the range of possible values (for integers) or what level of precision is necessary (for real numbers). The biggest distinction is between integer types and real numbers (which contain decimal points). Many of the types can take an optional Length attribute, limiting their size (in the corresponding tables, the square brackets,, indicate an optional parameter to be put in parentheses, while parentheses themselves indicate required arguments). Choosing your column types correctly not only dictates what information can be stored and how but also affects the database's overall performance. Within each of these, there are a number of variantssome of which are MySQL-specificyou can use. There are three primary categories, as is true for almost every database application: ![]() When creating the database, as you will do at the end of this chapter, MySQL requires that you define what sort of information each field will contain. ![]() Once you have identified all of the tables and columns that the database will need, you should determine each column's data type.
0 Comments
Leave a Reply. |