Solution : https://service.sap.com/sap/support/notes/873596 (SAP Service marketplace login required)
Key words : 
symptom exception cx_sy_open_sql_db occurs due, solution create message number, terms cx_sy_open_sql_db, dump occurs, error message, message class, single values, selection-sel_where, mass reason, selection request
Related Notes : 
       
| 1165460 | |
| 330416 | Sel.cond.>8kbytes: ABAP dump SAPSQL_WHERE_CANT_SCAN |