{{ transformations:SelectColumnsWithLookupAction.png}}
====== SELECT COLUMNS  BY LOOKUP ======
Category: Transform / Advanced\\

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=====Description=====
This action selects (keeps) columns which names are listed in another table. \\

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=====Use cases=====
This action is typically used when the names of columns to select are not known in advance and have to be obtained dynamically during a calculation.

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=====Action settings=====
^Setting^Description^
|Table|Select the table containing the column name values.|
|Column|Select the column in the selected table that contains the column name values.|
|Ignore case|When selected, the case is not considered when matching column names in the current dataset to the column name\\ values in the second dataset.|
The reference to the second table will appear as a dotted line connecting this action to the second dataset in the application window.\\

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=====Examples=====

**Example:** Keep only the columns in Table 1 that are listed in Table 2 (River, Length (km), and Outflow).\\
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**Table 1:** River lengths.
^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  |

**Table 2:** Columns to select (keep)
^Heading names^
|River|
|Length (KM)|
|Outflow|

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**Action parameters:**
>Table is "Table 2"
>Columns is "Heading names" (in Table 2)
>Ignore case is "checked"
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**Result table:** 
^River  ^Length (km)  ^Outflow  ^  
| Nile  |  6650|Mediterranean  | 
| Amazon  |  6400|Atlantic Ocean  |
| Yangtze  |  6300|East China Sea  |
| Mississippi  |  6275|Gulf of Mexico  |
If //Ignore case// was not checked, the "Length (km)" column would not have been selected.

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====Community examples====
  * [[https://community.easymorph.com/t//1475/1|Finding all projects with particular action]] ([[https://community.easymorph.com/uploads/short-url/cM8AssOT6zQXD8JDr9adUAy2sDM.morph|Project]]; Module: //Main//; Group: //Tab 1//; Table: //Projects with sandboxes//; Action position: //2//)

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=====See also=====
  * [[transformations:remove|Remove columns]]
  * [[transformations:lookuprename|Rename columns by lookup]]
  * [[transformations:select|Select columns]]