训练测试将 mysql 记录拆分为视图答案

【问题标题】：Train test split mysql records into views训练测试将 mysql 记录拆分为视图
【发布时间】：2021-08-28 05:21:39
【问题描述】：

如何创建两个视图，一个用于训练数据，另一个用于测试数据 70:30 在 mySql 中拆分。

CREATE VIEW training_data
AS
SELECT Posts.post_content as post_content,
    CASE 
        WHEN (Posts.post_title like '%covid%corona%covid19%' or Posts.post_content like '%covid%corona%covid19%') THEN 1 
        ELSE 0
    END AS tag 
FROM Posts;

CREATE VIEW test_data
AS
SELECT Posts.post_content as post_content,
    CASE 
        WHEN (Posts.post_title like '%covid%corona%covid19%' or Posts.post_content like '%covid%corona%covid19%') THEN 1 
        ELSE 0
    END AS tag 
FROM Posts;

【问题讨论】：

枚举（ROW_NUMBER 函数），同时按一些唯一的表达式排序，然后根据这个数字和提供所需关系的表达式进行选择。
你能帮我举个例子吗，我对 SQL 很陌生

标签： mysql train-test-split

【解决方案1】：

CREATE VIEW training_data
AS
WITH cte AS ( SELECT Posts.post_content as post_content,
                     CASE WHEN Posts.post_title like '%covid%corona%covid19%'
                          THEN 1
                          WHEN Posts.post_content like '%covid%corona%covid19%' 
                          THEN 1 
                          ELSE 0 END AS tag,
                     ROW_NUMBER() OVER (ORDER BY id) rn
              FROM Posts )
SELECT post_content, tag
FROM cte
WHERE rn MOD 10 IN (0,1,3,4,6,7,9);

和

CREATE VIEW test_data
AS
WITH cte AS ( SELECT Posts.post_content as post_content,
                     CASE WHEN Posts.post_title like '%covid%corona%covid19%'
                          THEN 1
                          WHEN Posts.post_content like '%covid%corona%covid19%' 
                          THEN 1 
                          ELSE 0 END AS tag,
                     ROW_NUMBER() OVER (ORDER BY id) rn
              FROM Posts )
SELECT post_content, tag
FROM cte
WHERE rn MOD 10 IN (2,5,8);

考虑到 - 由于全扫描，这两个查询都很慢。我建议您将带有tag 表达式的生成列添加到表结构中以进行改进。

【讨论】：