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--- transformations:merge [2018/04/30 09:44] – dmitry
+++ transformations:merge [2025/01/13 16:11] (current) – craigt
@@ Line 1: / Line 1: @@
-===== Merge another table =====
+{{ transformations:MergeAction.png}}
+====== MERGE ANOTHER TABLE ======
+Category: Transform / Basic\\
-This transformation appends one or more columns from another table where certain columns in both tables match.
+\\
+=====Description=====
+This action appends one or more columns from another table where the values in certain columns in both tables match. The action is similar to the SQL join, with four modes:  Lookup, Left Join, Full Join, and Inner Join.
-There are three possible merge modes:
+\\
+=====Use cases=====
+  * (Lookup Mode) Look up replacement values for common misspellings or abbreviations.
+  * (Left Join Mode) Blend in additional data from other tables into the primary dataset.
+  * (Full Join Mode) Combine two entire datasets to be cleaned and consolidated downstream.
+  * (Inner Join Mode) Connect only rows from both tables where the values in the selected fields match.
-  * Lookup Mode -- get **first** matching combination from the other table. If there are other combinations they are ignored.
+\\
-  * Left Join Mode -- get **all** matching combinations from the other table. It can increase number or rows in the current table.
+=====Action settings=====
-  * Full Join Mode -- include all combinations of keys from both tables. Equivalent to the full outer join in SQL.
+^Setting^Description^
+|Add columns from table|Select a table that will return columns to the current dataset where values match.|
+|Where all these columns match|Select the columns within the current dataset (left drop-down) and the second dataset (right drop-down) where\\ values will match.  To define multi-columnar matches, use the //Add more matching columns// to select additional matching columns in each dataset.|
+|Merge mode|Options:\\  //Lookup// (for each row in this table, get any one matching row from the second table and ignore other matches),\\ //Left join// (for each row in this table add all matching rows from the second table),\\ //Full join// (add matching and non-matching rows from both tables)\\ //Inner join// (add rows that match in both tables).|
+|Return columns|From the list, select the columns from the second dataset that will be appended to the current dataset.|
+The reference to the second table will appear as a dotted line connecting this action to the second dataset in the application window.
-EXAMPLE
+\\
+=====Remarks=====
+Matching is case-sensitive.
-**Table 1:** The longest rivers in the world
+Values must be identical (equal) to be matched. If another matching mode is needed (e.g. "Starts with") use the [[transformations:match|Match]] action first to do the matching.
-^  River  ^  Length (km)  ^  Continent  ^
+For an inner join use the [[transformations:keepremovematching|Keep/remove matching]] action before merging to keep only the overlapping subset of values in the matching columns.
-| Nile  |  6650  |  Africa  |
-| Amazon  |  6400  |  South America  |
-| Yangtze  |  6300  |  Asia  |
-| Mississippi  |  6275  |  North America  |
-**Table 2:** The outflow
-^  River  ^  Outflow  ^
+\\
-| Nile  |  Mediterranean  |
+=====Examples=====
-| Amazon  |  Atlantic Ocean  |
-| Yangtze  |  East China Sea  |
-| Mississippi  |  Gulf of Mexico  |
+====Example #1====
+>Merge the "Outflow" column of Table 2 into Table 1 based on matching values in the "Rivers" columns.  Keep only rows that match in both tables.
-**Objective:** Merge the "Outflow" column of Table 2 into Table 1
+===Before (source table)===
+Table 1: The rivers of the world
+^River  ^Continent  ^
+| Nile  |Africa  |
+| Amazon  |S. Amer.  |
+| Yangtze  |Asia  |
+| Mississippi  |North America  |
-**Transformation:**
+Table 2: The outflow
+^River  ^Outflow  ^
+| Nile  |Mediterranean  |
+| Amazon  |Atlantic Ocean  |
-  * Add columns from table: Table 2
+===After (result table)===
-  * Column: Outflow
+^River  ^Continent  ^Outflow  ^
-  * Merge mode: Add more rows to this table and all matching rows from Table 2 (i.e. do left join)
+| Nile  |Africa  |**Mediterranean**  |
+| Amazon  |S. Amer.  |**Atlantic Ocean**  |
-**Result:**
+===Action parameters===
+> Add columns from table: Table 2
+> Where values in Table 1's "River" column match Table 2's "River" column
+> Merge mode: Inner join
+> Return column: Outflow
-^  River  ^  Length (km)  ^  Continent  ^  Outflow  ^
-| Nile  |  6650  |  Africa  |  Mediterranean  |
-| Amazon  |  6400  |  South America  |  Atlantic Ocean  |
-| Yangtze  |  6300  |  Asia  |  East China Sea  |
-| Mississippi  |  6275  |  North America  |  Gulf of Mexico  |
-=== Limitations ===
+\\
-The resulting table after Merge can't have more than 134,217,728 rows.
+====Example #2====
+>Merge the "Outflow" column of Table 2 into Table 1 based on matching values in the "Rivers" columns.
-=== See also ===
+===Before (source table)===
+Table 1: The rivers of the world
+^River  ^Continent  ^
+| Nile  |Africa  |
+| Amazon  |S. Amer.  |
+| Yangtze  |Asia  |
+Table 2: The outflow
+^River  ^Outflow  ^
+| Nile  |Mediterranean  |
+| Amazon  |Atlantic Ocean  |
+| Yangtze  |East China Sea  |
+===After (result table)===
+^River  ^Continent  ^Outflow  ^
+| Nile  |Africa  |**Mediterranean**  |
+| Amazon  |S. Amer.  |**Atlantic Ocean**  |
+| Yangtze  |Asia  |**East China Sea**  |
+===Action parameters===
+> Add columns from table: Table 2
+> Where values in Table 1's "River" column that match Table 2's "River" column
+> Merge mode: Left join
+> Return column: Outflow
+\\
+=====Community examples=====
+  * [[https://community.easymorph.com/t//1273/8|Split Excel spreadsheets into multiple spreadsheets]] ([[https://community.easymorph.com/uploads/short-url/klG62NjaDDRQ2VXvo1xtFZJUYjK.morph|Project]]; Module: //Main//; Group: //Tab 1//; Table: //Spreadsheet A.xlsx//;\\ Action position: //2//)
+  * [[https://community.easymorph.com/t//1489/3|How to calculate YoY change using self-join]] ([[https://community.easymorph.com/uploads/short-url/40p81AvBk4V0GKWU3IHpy1evo2K.morph|Project]]; Module: //Main//; Group: //Self-join//; Table: //This year//; Action position: //2//)
+  * [[https://community.easymorph.com/t//1652/2|Which technique for grouping many columns of data together (i.e. 50+ columns)]] ([[https://community.easymorph.com/uploads/short-url/ub3zV5WsGF4rWqJQMb7oEtPReqy.morph|Project]]; Module: //Main//; Group: //Tab 1//; Table: //Table 2//; Action position: //4//)
+  * [[https://community.easymorph.com/t//2041/6|Join 2 tables with multi criterions equal and not equals in where]] ([[https://community.easymorph.com/uploads/short-url/kNkqMsDYMJjzjiN4C5g8O4g3YlA.morph|Project]]; Module: //Main//; Group: //Tab 1//; Table: //Join//; Action position: //2//)
+  * [[https://community.easymorph.com/t//2421/8|“Merge another table” action - merge all columns (independently of the column name)]] ([[https://community.easymorph.com/uploads/short-url/jHsMLkfW9YZVmGYNYtayhOt1VkJ.morph|Project]]; Module: //Merge//; Group: //Merge//;\\ Table: //Merge tables//; Action position: //2//)
+\\
+=====See also=====
   * [[transformations:append|Append another table]]
+  * [[transformations:lookup|Lookup]]
+  * [[transformations:intervalmerge|Interval merge]]