## Running queries

When you don’t need a transaction or run single queries, you can run queries directly on the pool; the pool will use one of its connection to run the query and return the result to you.

Here is how to run simple queries:

    client.query("SELECT * FROM users WHERE id='julien'") { |ar_err,ar|
      if (ar_err == nil)
        result = ar
        puts "Got #{result.size()} rows "
      else
        puts "Failure: #{ar_err.get_message()}"
      end
    }

### Prepared queries

You can do the same with prepared queries.

The SQL string can refer to parameters by position, using the database syntax {PREPARED_PARAMS}

    require 'vertx-sql-client/tuple'
    client.prepared_query("SELECT * FROM users WHERE id=?", VertxSqlClient::Tuple.of("julien")) { |ar_err,ar|
      if (ar_err == nil)
        rows = ar
        puts "Got #{rows.size()} rows "
      else
        puts "Failure: #{ar_err.get_message()}"
      end
    }

Query methods provides an asynchronous `RowSet` instance that works for SELECT queries

    client.prepared_query("SELECT first_name, last_name FROM users") { |ar_err,ar|
      if (ar_err == nil)
        rows = ar
        rows.each do |row|
          puts "User #{row.get_string(0)} #{row.get_string(1)}"
        end
      else
        puts "Failure: #{ar_err.get_message()}"
      end
    }

or UPDATE/INSERT queries:

    require 'vertx-sql-client/tuple'
    client.prepared_query("INSERT INTO users (first_name, last_name) VALUES (?, ?)", VertxSqlClient::Tuple.of("Julien", "Viet")) { |ar_err,ar|
      if (ar_err == nil)
        rows = ar
        puts rows.row_count()
      else
        puts "Failure: #{ar_err.get_message()}"
      end
    }

The `Row` gives you access to your data by index

    puts "User #{row.get_string(0)} #{row.get_string(1)}"

or by name

    puts "User #{row.get_string("first_name")} #{row.get_string("last_name")}"

The client will not do any magic here and the column name is identified with the name in the table regardless of how your SQL text is.

You can access a wide variety of of types

    firstName = row.get_string("first_name")
    male = row.get_boolean?("male")
    age = row.get_integer("age")

    # ...

You can cache prepared queries:

    # Enable prepare statements caching
    connectOptions['cachePreparedStatements'] = true

### Batches

You can execute prepared batch

    require 'vertx-sql-client/tuple'

    # Add commands to the batch
    batch = Array.new
    batch.push(VertxSqlClient::Tuple.of("julien", "Julien Viet"))
    batch.push(VertxSqlClient::Tuple.of("emad", "Emad Alblueshi"))

    # Execute the prepared batch
    client.prepared_batch("INSERT INTO USERS (id, name) VALUES (?, ?)", batch) { |res_err,res|
      if (res_err == nil)

        # Process rows
        rows = res
      else
        puts "Batch failed #{res_err}"
      end
    }