如何从多个连接表 MySQL 中选择不同的最大值 [英] How to select distinct max value from multiple join table MySQL

问题描述

这是我当前选择数据的查询:

This is my current query for selecting data:

select a.No_Registrasi, a.Nama_CTKI, b.Nama_Negara, c.ID_Rad, d.ID_Lab
FROM tb_registrasi a 
JOIN tb_negara_tujuan b
    ON a.ID_Negara = b.ID_Negara
JOIN tb_radiologi c
    ON a.No_Registrasi = c.No_Registrasi
JOIN tb_laboratorium d
    ON a.No_Registrasi = d.No_Registrasi

结果如下:

我如何区分 ID_Rad 和 ID_Lab，我需要每个 ID_Rad 和 ID_Lab 的最大值，所以它会是这样的:

How do i distinct those ID_Rad and ID_Lab and I need the max value from each ID_Rad and ID_Lab so it will be like this:

推荐答案

使用GROUP BY和MAX，试试这个；)

select a.No_Registrasi, a.Nama_CTKI, b.Nama_Negara, CONCAT('RA-', MAX(substring(c.ID_Rad, 4) + 0)) AS ID_Rad, CONCAT('Lab-',MAX(substring(d.ID_Lab, 5) + 0)) AS Id_Lab
FROM tb_registrasi a 
JOIN tb_negara_tujuan b
    ON a.ID_Negara = b.ID_Negara
JOIN tb_radiologi c
    ON a.No_Registrasi = c.No_Registrasi
JOIN tb_laboratorium d
    ON a.No_Registrasi = d.No_Registrasi
GROUP BY a.No_Registrasi, a.Nama_CTKI, b.Nama_Negara

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