Lookup() looks into a table that is already loaded and returns the value of field_name corresponding to the first
occurrence of the value match_field_value
in the field match_field_name.
The table can be the current table or another table previously loaded.
Name of the field for which the return value is required. Input value must be given as a string (for example, quoted literals).
match_field_name
Name of the field to look up match_field_value in. Input value must be given as a string (for example, quoted literals).
match_field_value
Value to look up in match_field_name field.
table_name
Name of the table in which to look up the value. Input value must be given as a string (for example quoted literals).
If table_name is omitted the current
table is assumed.
Information noteArguments without quotes refer to the current table. To refer to other tables, enclose an argument in single quotes.
Limitations:
The order in which the search is made is the load
order, unless the table is the result of complex operations such as joins,
in which case, the order is not well defined. Both field_name
and match_field_name must be fields
in the same table, specified by table_name.
If no match is found, NULL
is returned.
Load script
Load the following data as an inline load in the data load editor to create the example below.
ProductList:
Load * Inline [
ProductID|Product|Category|Price
1|AA|1|1
2|BB|1|3
3|CC|2|8
4|DD|3|2
] (delimiter is '|');
OrderData:
Load *, Lookup('Category', 'ProductID', ProductID, 'ProductList') as CategoryID
Inline [
InvoiceID|CustomerID|ProductID|Units
1|Astrida|1|8
1|Astrida|2|6
2|Betacab|3|10
3|Divadip|3|5
4|Divadip|4|10
] (delimiter is '|');
Drop Table ProductList;
For more information about using inline loads, see Inline loads.
Create a visualization
Create a table visualization in a Qlik Sense sheet. Add fields ProductID, InvoiceID, CustomerID, Units, and CategoryID to the table.
Result
Resulting table
ProductID
InvoiceID
CustomerID
Units
CategoryID
1
1
Astrida
8
1
2
1
Astrida
6
1
3
2
Betacab
10
2
3
3
Divadip
5
2
4
4
Divadip
10
3
Explanation
The sample data uses the Lookup() function in the following form:
The Lookup() function is used to build the OrderData table. It specifies the third argument as ProductID. This is the field for which the value is to be looked up in the second argument 'ProductID' in the ProductList, as denoted by the enclosing single quotes.
The function returns the value for 'Category' (in the ProductList table), loaded as CategoryID.
The drop statement deletes the ProductList table from the data model because it is not required, which leaves the resulting OrderData table.
Information noteThe Lookup() function is flexible and can access any previously loaded table. However, it is slow compared with the Applymap() function.
