SQL多行作为列（优化）

我不明白您为什么在

group_concat()

SET @sql = NULL;SELECt    GROUP_CONCAt(DISTINCT        CONCAt('MAX(CASE WHEN ckm.colkey = ', colkey, ' THEN ccd.value END) AS ',      CONCAt('ExtraColumn_', colkey, ''))    ) INTO @sqlFROM test_customkeymapping;SET @sql = CONCAt('SELECt c.Name, ', @sql, '         FROM customers c        LEFT JOIN customercustomdatarels ccdr          ON c.Id = ccdr.customer        LEFT JOIN customdatas cd          ON cd.Id = ccdr.customdata        LEFT JOIN test_customkeymapping ckmON cd.key = ckm.customkey        GROUP BY c.Id');PREPARE stmt FROM @sql;EXECUTE stmt;

注意：这未经测试，但是想法是相同的。在工作中使用main

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