Variable in postgreSQL query

Have you looked at MS-Query? It is part of Excel (Data -> From Other Sources -> MS Query).

What I recommend is work out the SQL that you want using WinSQL or some other tool. Hard code any restrictions that don't change into the SQL. Hard code the parameters you wish to pass with temporary values.

Then open MS-Query and turn off the wizard. Make the connection to the database you want. This will bring up a list of tables in the database. Close this list.

Click on the SQL button. Copy and paste your SQL into the window. If the query is simple enough, it will display graphically. You will see the various where clauses in the criteria area of the graphical query outline. For those queries you wish to pass at runtime, replace the hard coding with [Prompt Text]. This will prompt you for an entry for this field when the query is run.

Click on the exit door icon and the data will be returned to the workbook. If you right click in the returned data area, you get a dropdown menu. One of the items is parameters. Select that item and one of the options is to get the value from a cell on the spreadsheet. This cell could contain a formula, or a data validation of allowed values or whatever you want.

If the query is complex and cannot be displayed graphically, then use the technique in this article: http://www.utteraccess.com/wiki/index.php/MS_Query.

This process rewrites the SQL code and substitutes it for the connection string. It is not limited to just normal parameters. I've used it to switch between database tables or add a dynamic list of models for an IN clause generated elsewhere on the spreadsheet. In other words, I don't reprogram my SQL, I fill out data on the spreadsheet and it rewrites the code for me.