MySQL之procedure analyse()函数

你还在为MySQL表结构该选择什么类型字段而郁闷?你还在为MySQL字段该选择多少长度而纠结?给你一个武林秘籍吧~也是我今天偷学来的=。=

简介

procedure analyse()函数是MySQL内置的对MySQL字段值进行统计分析后给出建议的字段类型。

语法

procesure analyse(max_elements,max_memory)

  • max_elements
    指定每列非重复值的最大值,当超过这个值的时候,MySQL不会推荐enum类型。
  • max_memory
    analyse()为每列找出所有非重复值所采用的最大内存大小。

实战演练

# 对t1表所有的列进行分析
wing@3306>show create table t1;
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| t1 | CREATE TABLE `t1` (
`id` int(11) DEFAULT NULL,
`name` varchar(16) DEFAULT NULL,
`score` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
wing@3306>select * from t1 procedure analyse(4);
+---------------+-----------+-----------+------------+------------+------------------+-------+-------------------------+-------------+--------------------------------+
| Field_name | Min_value | Max_value | Min_length | Max_length | Empties_or_zeros | Nulls | Avg_value_or_avg_length | Std | Optimal_fieldtype |
+---------------+-----------+-----------+------------+------------+------------------+-------+-------------------------+-------------+--------------------------------+
| wing.t1.id | 1 | 200000 | 1 | 6 | 0 | 0 | 100000.5000 | 116099.2790 | MEDIUMINT(6) UNSIGNED NOT NULL |
| wing.t1.name | 000jxc6V | zzznmkcX | 8 | 8 | 0 | 0 | 8.0000 | NULL | CHAR(8) NOT NULL |
| wing.t1.score | 1 | 100 | 1 | 3 | 0 | 0 | 50.4889 | 28.8768 | TINYINT(3) UNSIGNED NOT NULL |
+---------------+-----------+-----------+------------+------------+------------------+-------+-------------------------+-------------+--------------------------------+
3 rows in set (0.14 sec)