excel 保留重复行（Power Query 之 M 语言）
数据源：
“姓名”“基数”“个人比例”“个人缴纳”“公司比例”“公司缴纳”“总计”，共7列7行数据，其中姓名列，第1、2行与第6、7行内容重复
目标：
留下第1、2、6、7姓名列中内容重复的行
操作过程：
选取指定列》【主页】》【保留行】》【保留重复项】
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M公式：
= let columnNames = {"指定列名"}, addCount = Table.Group(步骤名, columnNames, {{"Count", Table.RowCount, type number}}), selectDuplicates = Table.SelectRows(addCount, each [Count] > 1), removeCount = Table.RemoveColumns(selectDuplicates, "Count") in Table.Join(步骤名, columnNames, removeCount, columnNames, JoinKind.Inner)
说明：
= let?columnNames = {"指定列名"}, addCount = Table.Group(步骤名, columnNames, {{"Count", Table.RowCount, type number}}), selectDuplicates = Table.SelectRows(addCount, each [Count] > 1), removeCount = Table.RemoveColumns(selectDuplicates, "Count") in Table.Join(步骤名, columnNames, removeCount, columnNames, JoinKind.Inner)
- 给指定的列名一个说法，叫作“columnNames”
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= let columnNames = {"指定列名"},?addCount = Table.Group(步骤名, columnNames, {{"Count", Table.RowCount, type number}}), selectDuplicates = Table.SelectRows(addCount, each [Count] > 1), removeCount = Table.RemoveColumns(selectDuplicates, "Count") in Table.Join(步骤名, columnNames, removeCount, columnNames, JoinKind.Inner)
- 【分组依据】计算指定列里各个值出现次数，并将这结果命名为addCount
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= let columnNames = {"指定列名"}, addCount = Table.Group(步骤名, columnNames, {{"Count", Table.RowCount, type number}}),?selectDuplicates = Table.SelectRows(addCount, each [Count] > 1), removeCount = Table.RemoveColumns(selectDuplicates, "Count") in Table.Join(步骤名, columnNames, removeCount, columnNames, JoinKind.Inner)
- 【保留行】保留“Count”列中值大于1的行
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= let columnNames = {"指定列名"}, addCount = Table.Group(步骤名, columnNames, {{"Count", Table.RowCount, type number}}), selectDuplicates = Table.SelectRows(addCount, each [Count] > 1),?removeCount = Table.RemoveColumns(selectDuplicates, "Count")?in Table.Join(步骤名, columnNames, removeCount, columnNames, JoinKind.Inner)
- 【删除列】将“Count”列删除
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= let columnNames = {"指定列名"}, addCount = Table.Group(步骤名, columnNames, {{"Count", Table.RowCount, type number}}), selectDuplicates = Table.SelectRows(addCount, each [Count] > 1), removeCount = Table.RemoveColumns(selectDuplicates, "Count") in?Table.Join(步骤名, columnNames, removeCount, columnNames, JoinKind.Inner)
- 将原表和只保留重复值的表进行【合并查询】，连接种类使用“内部”
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将所有步骤拆分如图所示。
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其中核心部分：
addCount = Table.Group( 更改的类型,"姓名", {{"Count", Table.RowCount, type number}}),
selectDuplicates = Table.SelectRows(addCount, each [Count] > 1),
removeCount = Table.RemoveColumns(selectDuplicates, "Count"),
最后一步 = Table.Join(更改的类型, "姓名", removeCount, "姓名", JoinKind.Inner)
最终效果：
数据只剩下姓名列中重复的四行数据
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多说一句：
好吧，我承认，我被这个公式惊到了！这其实已经不是一个简单的公式，而是一段M代码，这不是有let开头，in结尾么……
……