Power Query - 可以使用 SQL 查询范围吗？答案

【问题标题】：Power Query - Can a range be queried using SQL?Power Query - 可以使用 SQL 查询范围吗？
【发布时间】：2022-04-20 01:59:09
【问题描述】：

我有一个名为 tDetails 的范围。如何使用 SQL 进行查询？

我单击我的范围，然后在 Power Query 选项卡上单击“从表/范围”。这将打开 Power Query 编辑器。

在高级编辑器中，我看到如下内容：

let
    Source = Excel.CurrentWorkbook(){[Name="tDetails"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"User ID", type text},
    {"Company", type text}, 
    {"State", type text},
    {"Billed", type Int65.Type}})
in
    #"Changed Type"

如何查询这些数据？我需要做以下事情：

SELECT 'UserID'   = "User ID"
,      'Discount' = "Billed" * .51
,      'Note'     = CASE WHEN State = 'NY' THEN 'Standard'
                         WHEN State = 'OH' THEN 'Second'
                         WHEN State = 'CA' THEN 'Third'
                         ELSE 'Fourth' END
FROM    Source
WHERE   "State"   = "NY"

另外，这里可以使用临时表吗？

SELECT 'UserID'   = "User ID"
,      'Discount' = "Billed" * .51
INTO    #UserDiscount
FROM    Source
WHERE   "State"   = "NY"

SELECT * FROM #UserDiscount ORDER BY Discount DESC

这些是超级基本的例子。我真正需要做的事情要复杂得多，但这会给我一个起点。

谢谢！

【问题讨论】：

愿你在使用 ADODB 来连接 Excel 文件或表格。链接：1、2、3 4、5
analystcave.com/excel-using-sql-in-vba-on-excel-data

标签： powerquery m

【解决方案1】：

我认为等效的 Power Query 会是

    let
    Source = Excel.CurrentWorkbook(){[Name="tDetails"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"User ID", type text},
    {"Company", type text}, 
    {"State", type text},
    {"Billed", type Int65.Type}})
    #"Filtered Rows" = Table.SelectRows(#"Changed Type", each ([State] = "NY")),
    #"Added Custom" = Table.AddColumn(#"Filtered Rows", "Discount", each [Billed]*0.51),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "UserID", each [UserID]),
    #"Removed Other Columns" = Table.SelectColumns(#"Added Custom1",{"UserID", "Discount", "Billed"})
in
    #"Removed Other Columns"

此外，Power Query 中 SQL #temp table 的等效项将使用 table variable。在电源查询中，每个步骤都是表变量，例如Source, #"Changed Type", #"Filtered Rows", #"Added Custom".... 包含在该步骤中评估的表。您可以在后续步骤中继续使用每个表变量中包含的表。

例如

    let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUcrPS1WK1YlWMgKyS8rzwWxjEDujKBUoEwsA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", Int64.Type}, {"Column2", type text}}),
    Custom0 = Table.SelectRows(#"Changed Type", each ([Column2] = "one")),
    Custom1 = Table.SelectRows(#"Changed Type", each ([Column2] = "two")),
    Custom2 = Table.SelectRows(#"Changed Type", each ([Column2] = "three")),
    Custom3 = Custom0&Custom1&Custom2
in
    Custom3

【讨论】：

【解决方案2】：

是的，但是您必须使用保留函数SqlExpression.ToExpression，并且根据 Power Query 可能需要 T-SQL 格式，您的 SQL 看起来不是“有效”的，因此您必须进行试验以及如何处理引号和重命名列。

详情见此页面：https://bengribaudo.com/blog/2021/07/13/5868/m-mysteries-sqlexpression-toexpression

查询：

// tDetails
// Input from Excel range. This example uses embedded data so you can replicate my result.
let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcspPUtJRcs7PK8kvzgey/CKBhKGRsYlSrE60kldqWhqKtL8HSNoADJRiYwE=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"User ID" = _t, Company = _t, State = _t, Billed = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"User ID", type text}, {"Company", type text}, {"State", type text}, {"Billed", Int64.Type}})
in
    #"Changed Type"

// Result
// Executes translated M code
let
    ReferenceTables = [Source = tDetails],
    Source = Expression.Evaluate(SQL, #shared)(ReferenceTables)
in
    Source

// SQL
// Translates SQL to M
let
  ReferenceTables = [Source = tDetails],
  SqlQuery = "SELECT [User ID] as UserID, Billed * 0.51 as Discount, 'Standard' as [Note] FROM Source WHERE State = 'NY'",
  TranslatedToM = SqlExpression.ToExpression(SqlQuery, ReferenceTables)
in
  TranslatedToM

t详情：

我的 SQL 有效： SELECT [User ID] as UserID, Billed * 0.51 as Discount, 'Standard' as [Note] FROM Source WHERE State = 'NY'

结果：

【讨论】：