sqler 2.0 提供了一个新的指令aggregate，注意这个和sql 的聚合函数不是一个概念，这个只是为了
方便api数据的拼接
参考格式
databases {exec = "SHOW DATABASES"
transformer = <<JS
// there is a global variable called `$result`,
// `$result` holds the result of the sql execution.
(function(){newResult = []
for ( i in $result ) {newResult.push($result[i].Database)
}
return newResult
})()
JS
}
tables {exec = "SELECT `table_schema` as `database`, `table_name` as `table` FROM INFORMATION_SCHEMA.tables"
transformer = <<JS
(function(){ $ret = {} for ( i in $result ) { if ( ! $ret[$result[i].database] ) {$ret[$result[i].database] = [];
}
$ret[$result[i].database].push($result[i].table)
}
return $ret
})()
JS
}
databasesAndTables { aggregate {databases = "current_databases"
tables = "current_tables"
}
}