There are effectively two different environments here. Expression.Evaluate needs one that has the functions from the standard library, while the environment consumed both by SqlExpression.ToExpression and by the function it produces needs to have just the tables referenced by the T/SQL-compatible query text. Naturally, a single combined environment (like the one produced by #shared) can fill both roles.

Sorry, my bad (had another Table1 in my queries) – so no question here.
But I will leave the „functionized“ version of the SqlExpression.ToExpression here without a constructed table in the environment. So this will work for all tables that exist in your current environment already:

(SqlExpression as text) =>
let
Source = Expression.Evaluate(SqlExpression.ToExpression(SqlExpression, #shared), #shared) (#shared)
in
Source

Thanks Curt – that is pretty awesome 🙂
One question though:
If I convert this to a function that just takes the SQL-code as a parameter, I need to add #shared to the innermost environment, whereas that statement evaluates without any problems as a standalone expression. It seems that this will make Table1 part of the outer #shared-environments as well, which is fine – just that I don’t understand why this syntax actually works. So any explanation would be very welcomed!

(SqlExpression as text) =>
let
Source = Expression.Evaluate( SqlExpression.ToExpression( SqlExpression, [Table1=#table(type table [Column1 as text, Column2 as number], {{„X“, 1}, {„Y“, 2}})] & #shared) , #shared) (shared)
in
Source

SqlExpression.ToExpression(„select Column1 from Table1 where Column2 = 1“, [Table1=#table(type table [Column1 as text, Column2 as number], {{„X“, 1}, {„Y“, 2}})])

The concatenation operator („&“) works on text, lists, records and tables.

Hello Meng Zong,

I must confess that your first example cannot work in Excel from my point of view. If both variables are steps in the same query, then #shared cannot be the solution because #shared delivers the Global Environment and no variable from inside the same query. So in the described case you always have to go for the solution Expression.Evaluate („A“,[A=A]). BUT: I would rather solve the problem described by you with a parameterized function., reading the user’s table selection from the UI (propably Excel) and use this as input parameter for the table selection in Excel or Power BI Desktop.

Cheers,
Lars

Hey Maxim,

thanks for your positiv feedback. I wasn’t aware, that „&“ combines two records. Thanks for that hint 🙂

Cheers,
Lars