UPDATE
The following structure defines the SQL update syntax in LiteDB. Keyworks and function names are case-insensitive.

  UPDATE <collection>
  SET <key0> = <exprValue0> [,<keyN> = <exprValueN>] | <newDoc>
[ WHERE <filterExpr> ]
collection is the name of the collection where the documents will be inserted.
Every key is the attribute name in the document and the corresponding exprValue is an expression that returns the desired value. For more info, see Expressions.
newDoc is a valid JSON object.
If the form <key> = <exprValue> is used in the SET clause, the informed fields will be updated or created in every document returned by the WHERE clause.
If newDoc is used in the SET clause, the documents returned by the WHERE clause will be entirely replaced by newDoc.
filterExpr is any valid filter expression. For more info, check Where clause