Why map return [] ?

[Suliman via Digitalmars-d-learn]

On Friday, 14 April 2017 at 15:55:13 UTC, Rene Zwanenburg wrote:
> On Friday, 14 April 2017 at 15:49:00 UTC, Suliman wrote:
>> I found problem! ResultRange should be converted to array 
>> before it can be `map`ed
>
> That shouldn't be necessary. Can you post your complete code?

ResultRange MySQLTablesRange = mysqlconnection.query(`SELECT 
table_name FROM information_schema.tables;`);
auto x = 
MySQLTablesRange.map!(a=>a[0].coerce!string.split("_")[1]);
writeln(x);

output: []
while: MySQLTablesRange.array.map!...

output result