在 Postgresql 中使用聚合和汇总

Question

我有一个简单的查询，旨在根据其他列的 GROUP BY 聚合来汇总 total_miles：

SELECT 
    tiermetric AS tier,
    st AS state, 
    validation,
    'All' AS study_type,
    SUM(total_miles) as total_miles
FROM mu_schema.my_table
WHERE validation = 'VALID'
AND st = 'VA'
GROUP BY
    tiermetric,
    state,
    validation,
    study_type 
ORDER BY tiermetric

目前输出：

tier    state   validation  study_type  total_miles
TIER 2  VA      VALID       All         335.005721465211
TIER 2  VA      VALID       All         0.337142821958635
TIER 3  VA      VALID       All         13.3444415576409
TIER 3  VA      VALID       All         1651.56942736755
TIER 4  VA      VALID       All         6606.44868771768
TIER 4  VA      VALID       All         1399.72188798074

我希望它输出：

tier    state   validation  study_type  total_miles
TIER 2  VA      VALID       All         335.3421
TIER 3  VA      VALID       All         1664.9138
TIER 4  VA      VALID       All         8006.1704

我在这里做错了什么？我基本上只想按等级汇总里程。

Answer 1

您正在按 study_type 分组，这是一个列，在您的基础 table 中每个层都有两个不同的值。虽然您没有选择该列，但您使用常量 'All' 作为那个。因此，您只需从 GROUP BY 子句中删除 study_type 列，它就可以正常工作。

Answer 2

SELECT 
    tiermetric AS tier,
    st AS state, 
    validation,
    'All' AS study_type,
    SUM(total_miles) as total_miles
FROM mu_schema.my_table
WHERE validation = 'VALID'
AND st = 'VA'
GROUP BY
    tiermetric,
    state,
    validation
ORDER BY tiermetric

在 Postgresql 中使用聚合和汇总

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