Shulou(Shulou.com)05/31 Report--

In this issue, the editor will bring you about the common data types in the SQL database. The article is rich in content and analyzes and describes it from a professional point of view. I hope you can get something after reading this article.

Common data types in SQL database

First, we introduce the main data types supported by the SQL system, and all properties must have data types.

1. A string of fixed or variable length. The type CHAR (n) represents a string of fixed length of n characters. This means that if the attribute type is CHAR (n), the component corresponding to that attribute in any tuple is a string of n characters. V A RCHAR (n) represents a string of at most n characters. The component corresponding to this class attribute can be a string of 0 to n characters. SQ L allows reasonable casts between values of type string. If the string becomes a component value of a longer fixed-length string type, it is usually filled with trailing spaces. For example, the string 'foo', if it becomes the component value corresponding to an attribute of type CHAR (5), takes the value of' foo' (with two spaces on the second o). If the value of the component is compared to another string. The filled spaces are ignored.

two。 A fixed or variable length bit string. Similar to fixed and variable length strings, but the value is a bit string instead of a string. The type BIT (n) represents a bit string of length n, while BITVARYING (n) represents a bit string of length n at most.

3. Types INT or INTEGER (they are synonyms) represent typical integer values. The type SHORTIN T also represents an integer, but depending on the implementation, the number of bits allowed may be less (similar to the types int and shortt in C).

4. Floating point numbers can be represented in a variety of ways. We can use the type FLOAT or REAL (which are synonyms) to represent a typical floating point number. High-precision floating-point numbers can be obtained from the type DOUBLEPRECISION; the distinction between these types is also similar to the situation in C. S Q L also has a real number class with a fixed decimal point, for example, ECIM A L (n, d) allows n decimal digits, with the decimal point in the d place from the right. For example, 0 12 3. 45

Is a possible value for type DECIMA L (6, 2).

5. The date and time can be represented by the data types D A T E and T IM E. These values are essentially specially formatted strings. In fact, we can cast the date and time to a string type, or vice versa if the string is a meaningful date and time.

These are the common data types in the SQL database shared by the editor. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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