I'm having a issue with SAP connector when left joining multiple tables. Here is a simple example that causes the error:
left join PRPS
on GLPCA~PS_PSP_PNR = PRPS~PSPNR
left join EQUI
on PRPS~EQUNR = EQUI~EQUNR;
This is the error I'm receiving:
One strange thing is that if I change any of the "left join" to a "join" the query works.
Looking in the log:
10:18:30,925  - SQLQueryParserService.Parse() - About to parse query: SELECT GLPCA~GL_SIRID, PRPS~PSPNR, EQUI~EQNUM FROM GLPCA left join PRPS on GLPCA~PS_PSP_PNR = PRPS~PSPNR left join EQUI on PRPS~EQUNR = EQUI~EQUNR
So far everything looks OK, but later in the log:
10:18:31,375  - SQL Line(s): 10:18:31,375  - SELECT GLPCA~GL_SIRID PRPS~PSPNR EQUI~EQNUM FROM GLPCA LEFT 10:18:31,375  - JOIN PRPS ON GLPCA~PS_PSP_PNR = PRPS~PSPNR LEFT JOIN EQUI 10:18:31,375  - ON PRPS~EQUNR = EQUI~EQUNR
it looks like all commas have been removed. Which also the error points to "List must be separated with commas".
If that is the case, I don't know why they are removed since SAP recommends using commas "In Open SQL, all operands in lists can now be separated by commas and this is also the recommended way of separating them from Release 7.40, SP05"
Open SQL defines the subset of ABAP statements that enable direct access to data from the central database of the current AS ABAP. The SQL statement has to pass the SAP syntax check, otherwise the ABAP statements used to fetch the data will fail. Unfortunately the bad error message in this case is generated by the SAP syntax check, so until SAP makes a correction in their syntax check, we have to live with it.
It is not possible to change the SQL connector to use Native SQL instead of Open SQL.
Maybe you can split your SQL statement into several statements and merge the result in the script? However I don't have any example of how to do that.