whereClause

The attribute expression that defines features to be included in the query. The where clause should follow standard SQL syntax similar to that discussed in the document SQL reference for query expressions used in ArcGIS

If the where clause includes dates, they must be correctly formatted based on the geodatabase datasource used in the service. Refer to Dates and time for date formats expected by different data sources.

ArcGISFeatureTable objects expect that any FieldType.GlobalId or FieldType.Guid parameters in the where clause are formatted as: '{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}'. All characters are uppercase, wrapped in curly braces and surrounded by single quotes.

If the where clause is used to populate an OgcFeatureCollectionTable, you can use a CQL2-TEXT or CQL2-JSON string as defined in the document OGC API - Features - Part3.