=gsSQL() - Is a sheets custom function that contains the full functionality of SQL SELECT statements. It is used as a custom function OR can be used from your Google Apps Script directly.
It is especially useful to perform Left/Right/Full joins and sub-queries (i.e. SELECT IN) between Sheets and/or ranges. It is also handy and quicker to read/write than the convoluted Google Sheets =QUERY() function.
I have written this for myself, but have made it an open source project for anybody to use.
Any comments, suggestions, improvements or help to improve would be greatly appreciated.