Question

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

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;

Answer 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，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。

训练测试将 mysql 记录拆分为视图

1 个答案: