<p>I have the following string expression in a PowerShell script:</p>

<pre><code>"select count(*) cnt from ${schema}.${table} where ${col.column_name} is null"
</code></pre>

<p>The schema and table resolve to the values of $schema and $table, respectively. However, an empty string is supplied for ${col.column_name}. How can I dot into the member of a variable as part of a string substitution?</p>

How about:
```
```
"select count(*) cnt from $schema.$table where $($col.column_name) is null"
```
```