You generally cannot download isql as a standalone executable from official SAP channels; it is bundled within larger client or server packages. Utility Guide - SAP Help Portal
The is a 64-bit command-line interface used to execute Transact-SQL (T-SQL) commands and manage SAP Adaptive Server Enterprise (formerly Sybase ASE). Unlike modern graphical tools, isql is valued for its lightweight footprint and scriptability in automated environments. Where to Download ASE ISQL 64-bit ase isql download 64 bit