如何在具有 WHERE 子句的 SQL 中查找最大列值？答案

【问题标题】：How to find a Maximum Column value in SQL which has a WHERE clause?如何在具有 WHERE 子句的 SQL 中查找最大列值？
【发布时间】：2020-05-11 19:48:11
【问题描述】：

我正在尝试用 SQL 编写一个过程。在将所有日期条目与传递的输入参数匹配后，我想从表中打印带有“最大分数”的记录。现在，代码只打印与指定日期对应的所有记录。我不确定在这种情况下如何使用 MAX()。

/* =========================================================
Procedure to find the Highest Movie Rating on a particular date.
Given, an inpDate (input Date) it first looks up all Movie Reviews
of that particular date.
Then, it checks a StandardizedReviews Table (sTbl) and
finds the MAXIMUM adjusted_score with the
Highest Review Score (the variable adjusted_score)
========================================================= */
Use StandardizedReviews
Drop Procedure if exists HighestReview;
GO

CREATE PROCEDURE HighestReview @inpDate DATE AS (
        SELECT sTbl.adjusted_score "Max Score"
        FROM dbo.StandardizedReviews sTbl
        WHERE CAST(sTbl.date as DATE) = CAST(@inpDate as DATE)
        GROUP BY sTbl.date, sTbl.adjusted_score
)
GO
exec HighestReview '2020-03-05'
GO

现在，我的输出看起来像：

但我希望它只显示得分为 100 的记录。谢谢。

【问题讨论】：

标签： sql select max where-clause

【解决方案1】：

您只需用 MAX() AS 'Max Score' 包装adjusted_score 值，这将只选择最高分。您还可以在您的组中删除对 sTbl.adjusted_score 的引用，并且仅按日期排序：

CREATE PROCEDURE HighestReview @inpDate DATE AS (
    SELECT MAX(sTbl.adjusted_score) AS 'Max Score'
    FROM dbo.StandardizedReviews sTbl
    WHERE CAST(sTbl.Date AS DATE) = CAST(@inpDate AS DATE)
    GROUP BY sTbl.Date
)

【讨论】：