## 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 ->
      if (ar.succeeded()) {
        def result = ar.result()
        println("Got ${result.size()} rows ")
      } else {
        println("Failure: ${ar.cause().getMessage()}")
      }
    })

### 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}

    client.preparedQuery("SELECT * FROM users WHERE id=?", Tuple.of("julien"), { ar ->
      if (ar.succeeded()) {
        def rows = ar.result()
        println("Got ${rows.size()} rows ")
      } else {
        println("Failure: ${ar.cause().getMessage()}")
      }
    })

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

    client.preparedQuery("SELECT first_name, last_name FROM users", { ar ->
      if (ar.succeeded()) {
        def rows = ar.result()
        rows.each { row ->
          println("User ${row.getString(0)} ${row.getString(1)}")
        }
      } else {
        println("Failure: ${ar.cause().getMessage()}")
      }
    })

or UPDATE/INSERT queries:

    client.preparedQuery("INSERT INTO users (first_name, last_name) VALUES (?, ?)", Tuple.of("Julien", "Viet"), { ar ->
      if (ar.succeeded()) {
        def rows = ar.result()
        println(rows.rowCount())
      } else {
        println("Failure: ${ar.cause().getMessage()}")
      }
    })

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

    println("User ${row.getString(0)} ${row.getString(1)}")

or by name

    println("User ${row.getString("first_name")} ${row.getString("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

    def firstName = row.getString("first_name")
    def male = row.getBoolean("male")
    def age = row.getInteger("age")

    // ...

You can cache prepared queries:

    // Enable prepare statements caching
    connectOptions.cachePreparedStatements = true

### Batches

You can execute prepared batch

    // Add commands to the batch
    def batch = []
    batch.add(Tuple.of("julien", "Julien Viet"))
    batch.add(Tuple.of("emad", "Emad Alblueshi"))

    // Execute the prepared batch
    client.preparedBatch("INSERT INTO USERS (id, name) VALUES (?, ?)", batch, { res ->
      if (res.succeeded()) {

        // Process rows
        def rows = res.result()
      } else {
        println("Batch failed ${res.cause()}")
      }
    })