SQLSelect -->iSQLQuery_ToString - Problem with Join on 2 or more Tables

Issue detected when attempting to create SQLString if 2 or more tables are necessary to JOIN.
the resulting SQL contains error and cannot be used.

Start by locating SQLSelect and iSQLQuery_ToString in the repository, then reproduce the issue with a query that joins two or more tables. Inspect the generated SQL and compare it with the valid join syntax required by the reported case; done means the resulting SQL can be used successfully for multi-table joins.

索引モデルが issue の本文から書いたものです。