SELECT count(*) FROM sapsr3.dfkkop WHERE vkont >= '000802037649' and vkont < '000802038649' ; +-------+ | L1 | +=======+ | 81196 | +-------+ 1 tuple (1.8s) SELECT count(*) FROM sapsr3.dfkkop WHERE vkont >= 000802037649 and vkont < '000802038649' ; +-------+ | L1 | +=======+ | 81196 | +-------+ 1 tuple (1.5s) SELECT count(*) FROM sapsr3.dfkkop WHERE vkont >= 000802037649 and vkont < 000802038649 ; conversion of string 'VI0802037717' to type int failed. Column "vkont" is defined as varchar(12), values are going from '000218123761' to 'ZZ0876213465'. 2nd statement is obviously doing some internal type conversion. 3rd statement fails. If there is done any kind of internal type conversion, I would expect that the outcome of this opereration must not depend on column's values.