1. A method for selecting by an intermediary device a database from a plurality of databases to forward a structured query language (SQL) query request based on a property of the SQL query request, the method comprising: (a) establishing, by a device intermediary to a plurality of clients and a plurality of databases, a plurality of server-side connections to the plurality of databases, the device establishing a pool of server-side connections to each database of the plurality of databases; (b) receiving, by the device from a client of the plurality of clients, a request to execute a structured query language (SQL) query included in the request; (c) parsing, by the device, the SQL query to identify one or more first properties of the SQL query that are exposed using policy expressions corresponding to a first policy for selecting a database to execute the SQL query; (d) evaluating, by the device responsive to the first policy, the one or more first properties of the SQL query to select a database to execute the SQL query, the one or more first properties of the SQL query identifying an action to be taken on a database; (e) selecting, by the device, a database from the plurality of databases based on a result of evaluation of the one or more first properties of the SQL query; (f) parsing, by the device, the SQL query to identify one or more second properties of the SQL query that are exposed using policy expressions corresponding to a second policy for selecting a server-side connection of the pool of server-side connections over which to forward the SQL query to the database; (g) evaluating, by the device responsive to the second policy, the one or more second properties of the SQL query to select a server-side connection of the pool of server-side connections over which to forward the SQL query to the database, the one or more second properties identifying connection characteristics of a database connection; (h) selecting, by the device, the server-side connection of the pool of server-side connections based on a result of evaluation of the one or more second properties of the SQL query; and (i) forwarding, by the device, the SQL query to the selected database via the server-side connection of the plurality of server-side connections.