Moodle in English

Is it a screen-shot, i.e. exactly as shown? The value of prefix is usually mdl.

The issue is that in the Ad-hoc database queries plugin, unlike the Config Reports plugin, the use of a question mark "?" in a query will throw the incorrect number of parameters error. Since this code uses the question mark (twice) to create the parameters in the url string, that is the problem.

The solutions to this are shown right on the page when you are editing an Ad-hoc query:

"You cannot use the characters :, ; or ? in strings in your query.

If you need them in output data (such as when outputting URLs), you can use the tokens %%C%%, %%S%% and %%Q%% respectively.
If you need them in input data (such as in a regular expression or when querying for the characters), you will need to use a database function to get the characters and concatenate them yourself. In Postgres, respectively these are CHR(58), CHR(59) and CHR(63); in MySQL CHAR(58), CHAR(59) and CHAR(63)."

In the example Ken posted below, you can see I used the CHAR(63) method, which works in both Ad-hoc reports plugin and the Config Reports plugin. You can %%Q%% in Ad-hoc reports as well if you want.