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
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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
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# 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) |
总结
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