I know, that it is not a good idea to write something in the database from server-side and it is better to use the b4j client. But is it harmless to read the values from server side with the following sub?
B4X:
Public Sub GetKG(user As String, key As String) As Map
Dim rs As ResultSet = sql.ExecQuery2("SELECT value FROM data WHERE user = ? AND key = ?", Array(user, key))
Do While rs.NextRow
Dim KGMap As Map
KGMap.Initialize
KGMap = serializator.ConvertBytesToObject(rs.GetBlob("value"))
Loop
rs.Close
Return KGMap
End Sub