Method: Sources.SelectFirst( … )

Use if you need flexible criteria for lookup of values from other Table Data Sources.
Returns the first row from the specified data source that matches the filter-expression after any optional specified sorting of the rows.
Note: This method is very flexible in what criteria you can apply when searching in other data sources. However, it can be very slow if a data source is large. For very fast search performance use the Sources.Find(…) or Sources.FindValue(…) methods instead.

Syntax

DataRow Sources.SelectFirst( string sourceName, string filterExpression, string sort = "" )

Method Parameters

string sourceName	Name of the Data Source to search in. The Data Source must be of the Table type which is the default returned data source by all Select Commands.
string filterExpression	Expression used to filter rows, similar to SQL. Example: "Cylinder=8 AND Price > AVG(Price)" For more specific documentation on the filter-syntax, check the Microsoft documentation for the DataView RowFilter Syntax [C#].
string sort	Optional value specifying the column to sort and direction. Example: "Price ASC"

Example

Below example shows how to lookup values in a lookup table in order to convert some input values, e.g. if the input source has values like R, G and B, but you want it to be Red, Green and Blue instead.
In below example a data source named Color contains a translation table with 2 columns named ColorCode and ColorName. Values are looked up via the ColorCode column to get the ColorName that is wanted.

if( !HasValue ) return;
var lookup = Sources.SelectFirst( "Colors", "ColorCode='" + Value + "'" );
if( lookup != null )
Value = lookup["ColorName"];

1 Syntax
2 Method Parameters
3 Example