You can do this in an SQL statement. If it's in an NPC script:
prontera,123,123,5 script sql_test 123,{
mes "Input player's char ID";
input .@charid;
next;
query_sql("SELECT `name`, `sex` FROM `char` WHERE `char_id` = '"+ .@charid +" LIMIT 1", .@name$, .@sex$);
if(getarraysize(.@name$) == 0){
mes "Unknown Char ID";
} else {
mes "Char ID: "+ .@charid;
mes "Char Name: "+ .@name$[0];
mes "Char Sex: "+ .@sex$[0];
}
close;
}
Untested, but should work.