Forum Discussion
Restrict rows retrieved by query?
The single-qoutes is needed as part of my SQL query to filter a string column in the SQL database
The 1st double-qoute stop the "free text query" and allows to insert a parameter
Ampersand is needed to merge the parameter with the SQL code around paramater
The 2nd double-qoute continue the "free text query"
I hope this explains the code.
Now back to your problem... 19 foreign keys "scary face". I assume that you users will need to be able to filter several parameters at once? This will force you to type SQL code from now until you retire. As I see it you will have to create 19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2 combinations of your code + create 19 parameters lists with a complete set of values for your user - and this will only give them the option to select a single value per parameter. I don't think this is the right path for you. You will need to many different variations of your code because consider that your user only select a parameter in a few of your lists, then the rest will be blank but if you query your SQL with WHERE a.Country = '' then you will only get the customer with no country value (blank), but what you really want is not to filter the country column in your SQL table, so you will somehow have to handle all the combinations of posible where clauses you need.
With single value per parameter I mean they will not be able to select both US and UK customers but only one of them - unless you make you parameters free text values. Then you will be able to chance the SQL to use IN instead of =, but your users will only get the wanted result if they learn to write the right text - using my example from before this would be 'US', 'UK' and your where clause should be "WHERE a.Country IN (" & CountryParameter & ")"
The single-qoutes is needed as part of my SQL query to filter a string column in the SQL database
The 1st double-qoute stop the "free text query" and allows to insert a parameter
Ampersand is needed to merge the parameter with the SQL code around paramater
The 2nd double-qoute continue the "free text query"
I hope this explains the code.
Now back to your problem... 19 foreign keys "scary face". I assume that you users will need to be able to filter several parameters at once? This will force you to type SQL code from now until you retire. As I see it you will have to create 19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2 combinations of your code + create 19 parameters lists with a complete set of values for your user - and this will only give them the option to select a single value per parameter. I don't think this is the right path for you. You will need to many different variations of your code because consider that your user only select a parameter in a few of your lists, then the rest will be blank but if you query your SQL with WHERE a.Country = '' then you will only get the customer with no country value (blank), but what you really want is not to filter the country column in your SQL table, so you will somehow have to handle all the combinations of posible where clauses you need.
With single value per parameter I mean they will not be able to select both US and UK customers but only one of them - unless you make you parameters free text values. Then you will be able to chance the SQL to use IN instead of =, but your users will only get the wanted result if they learn to write the right text - using my example from before this would be 'US', 'UK' and your where clause should be "WHERE a.Country IN (" & CountryParameter & ")"
sdjensen, that got me the solution I needed. Thanks so much, I'll Accept your answer.
I actually took a slightly different tack in the end. Instead of modifying the WHERE clause in the Advanced Editor, I created a filter on each column that referred to the parameter. So for a range of dates against a DateTime column in the database I created two parameters with type "any" and entered the formula
= Table.SelectRows(#"Reordered Columns", each [KeyDateTime] >= DateTimeZone.From(StartDate) and [KeyDateTime] <= DateTimeZone.From(EndDate))
and for a number column in the database that can contain nulls, I created a parameter with type "Text" and entered the formula
= Table.SelectRows(#"Filtered Rows2", each (Text.From([InspMethod]) = InspMethod) or (InspMethod = "ALL") or (([InspMethod] = null) and (InspMethod = "BLANK")))
So that the user can enter "ALL" to retrieve all rows including nulls, "BLANK" to retrieve rows with null, or a value to retrieve rows with that value.
The advantage of this approach is that I only need a generic query, not 19*18*17... queries or a complex one that tests for the presence of parameters, or all 19 parameters in every query with a convoluteted WHERE clause, etc. It appears that the query gets generated with the parameters it needs.
It seems to be working great.
Thanks for the lead and great information.
Regards,
Sam