== 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:

[source,java]
----
client.query("SELECT * FROM users WHERE id='julien'", ar -> {
  if (ar.succeeded()) {
    RowSet<Row> result = ar.result();
    System.out.println("Got " + result.size() + " rows ");
  } else {
    System.out.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}

[source,java]
----
client.preparedQuery("SELECT * FROM users WHERE id=$1", Tuple.of("julien"), ar -> {
  if (ar.succeeded()) {
    RowSet<Row> rows = ar.result();
    System.out.println("Got " + rows.size() + " rows ");
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});
----

Query methods provides an asynchronous `link:../../apidocs/io/vertx/sqlclient/RowSet.html[RowSet]` instance that works for _SELECT_ queries

[source,java]
----
client.preparedQuery("SELECT first_name, last_name FROM users", ar -> {
  if (ar.succeeded()) {
    RowSet<Row> rows = ar.result();
    for (Row row : rows) {
      System.out.println("User " + row.getString(0) + " " + row.getString(1));
    }
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});
----

or _UPDATE_/_INSERT_ queries:

[source,java]
----
client.preparedQuery("INSERT INTO users (first_name, last_name) VALUES ($1, $2)", Tuple.of("Julien", "Viet"),  ar -> {
  if (ar.succeeded()) {
    RowSet<Row> rows = ar.result();
    System.out.println(rows.rowCount());
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});
----

The `link:../../apidocs/io/vertx/sqlclient/Row.html[Row]` gives you access to your data by index

[source,java]
----
System.out.println("User " + row.getString(0) + " " + row.getString(1));
----

or by name

[source,java]
----
System.out.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

[source,java]
----
String firstName = row.getString("first_name");
Boolean male = row.getBoolean("male");
Integer age = row.getInteger("age");
----

You can cache prepared queries:

[source,java]
----
connectOptions.setCachePreparedStatements(true);
----

=== Batches

You can execute prepared batch

[source,java]
----
List<Tuple> batch = new ArrayList<>();
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 ($1, $2)", batch, res -> {
  if (res.succeeded()) {

    // Process rows
    RowSet<Row> rows = res.result();
  } else {
    System.out.println("Batch failed " + res.cause());
  }
});
----