同时,我们会展示两个图表:一个旅行图和一个实体关系图,帮助读者更好地理解整个概念。 1. Understanding Decimal Type in MySQL 在MySQL中,DECIMAL类型用于存储精确的小数数值,其语法为DECIMAL(M,D),其中M表示数字的总位数,而D则是小数点后面的位数。例如,DECIMAL(5,2)可以存储范围从-999.99到999.99的数值。 2. ...
Query OK, 1 row affected (0.00 sec) mysql> use utf8_test; Database changed mysql> create table person (name varchar(20)); Query OK, 0 rows affected (0.02 sec) mysql> desc person; +---+---+---+---+---+---+ | Field | Type | Null | Key | Default | Extra | +---+--...
MySQL 的 decimal 使用一个长度为 len 的 decimal_digit_t (int32) 的数组 buf 来存储 decimal 的数字, 每个 decimal_digit_t 最多存储 9 个数字, 用 intg 表示整数部分的数字个数, frac 表示小数部分的数字个数, sign 表示符号. 小数部分和整数部分需要分开存储, 不能混合在一个 decimal_digit_t 中, ...
This section discusses the characteristics of theDECIMALdata type (and its synonyms), with particular regard to the following topics: Maximum number of digits Storage format Storage requirements The nonstandard MySQL extension to the upper range ofDECIMALcolumns ...
在MySQL中,DECIMAL类型本身并不区分正负数,它只是一个数值类型。如果你需要确保某个DECIMAL字段只存储正数,可以通过以下几种方式实现: 使用CHECK约束: 使用CHECK约束: 在应用层进行检查: 在插入或更新数据时,在应用层代码中检查数值是否为正数。 使用触发器: ...
It's assumed that fixed-point values, DECIMAL and NUMERIC, in MySQL are not susceptible to rounding errors because they are exact numeric data types. Not true.
mysql> CREATE TABLE `tc_integer` ( `f_id` bigint(20) PRIMARY KEY AUTO_INCREMENT, `f_type` tinyint, `f_flag` tinyint(1), `f_num` smallint(5) unsigned ZEROFILL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; mysql> desc tc_integer; ...
This section discusses the characteristics of theDECIMALdata type (and its synonyms), with particular regard to the following topics: Maximum number of digits Storage format Storage requirements The nonstandard MySQL extension to the upper range ofDECIMALcolumns ...
DECIMAL Data Type In MySQL,DECIMAL(M,D)andNUMERIC(M,D)are the same, and both have a precision of exactlyMdigits. Leftover Digits Number of Bytes001–213–425–637–94 For example, aDECIMAL(18,9)column has nine digits on either side of the decimal point, so the integer part and the...
in bits following the keywordFLOAT in parentheses. MySQL also supports this optional precision specification, but the precision value is used only to determine storage size. 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...