SelectSubqueryTest.php

<?php

declare (strict_types=1);
namespace Drupal\KernelTests\Core\Database;


/**
 * Tests the Select query builder.
 *
 * @group Database
 */
class SelectSubqueryTest extends DatabaseTestBase {

  /**
   * Tests that we can use a subquery in a FROM clause.
   */
  public function testFromSubquerySelect() {

    // Create a subquery, which is just a normal query object.
    $subquery = $this->connection
      ->select('test_task', 'tt');
    $subquery
      ->addField('tt', 'pid', 'pid');
    $subquery
      ->addField('tt', 'task', 'task');
    $subquery
      ->condition('priority', 1);
    for ($i = 0; $i < 2; $i++) {

      // Create another query that joins against the virtual table resulting
      // from the subquery.
      $select = $this->connection
        ->select($subquery, 'tt2');
      $select
        ->join('test', 't', '[t].[id] = [tt2].[pid]');
      $select
        ->addField('t', 'name');
      if ($i) {

        // Use a different number of conditions here to confuse the subquery
        // placeholder counter, testing https://www.drupal.org/node/1112854.
        $select
          ->condition('name', 'John');
      }
      $select
        ->condition('task', 'code');

      // The resulting query should be equivalent to:
      // @code
      // SELECT t.name
      // FROM (SELECT tt.pid AS pid, tt.task AS task FROM test_task tt WHERE priority=1) tt
      //   INNER JOIN test t ON t.id=tt.pid
      // WHERE tt.task = 'code'
      // @endcode
      $people = $select
        ->execute()
        ->fetchCol();
      $this
        ->assertCount(1, $people, 'Returned the correct number of rows.');
    }
  }

  /**
   * Tests that we can use a subquery in a FROM clause with a LIMIT.
   */
  public function testFromSubquerySelectWithLimit() {

    // Create a subquery, which is just a normal query object.
    $subquery = $this->connection
      ->select('test_task', 'tt');
    $subquery
      ->addField('tt', 'pid', 'pid');
    $subquery
      ->addField('tt', 'task', 'task');
    $subquery
      ->orderBy('priority', 'DESC');
    $subquery
      ->range(0, 1);

    // Create another query that joins against the virtual table resulting
    // from the subquery.
    $select = $this->connection
      ->select($subquery, 'tt2');
    $select
      ->join('test', 't', '[t].[id] = [tt2].[pid]');
    $select
      ->addField('t', 'name');

    // The resulting query should be equivalent to:
    // @code
    // SELECT t.name
    // FROM (SELECT tt.pid AS pid, tt.task AS task FROM test_task tt ORDER BY priority DESC LIMIT 1 OFFSET 0) tt
    //   INNER JOIN test t ON t.id=tt.pid
    // @endcode
    $people = $select
      ->execute()
      ->fetchCol();
    $this
      ->assertCount(1, $people, 'Returned the correct number of rows.');
  }

  /**
   * Tests that we can use a subquery with an IN operator in a WHERE clause.
   */
  public function testConditionSubquerySelect() {

    // Create a subquery, which is just a normal query object.
    $subquery = $this->connection
      ->select('test_task', 'tt');
    $subquery
      ->addField('tt', 'pid', 'pid');
    $subquery
      ->condition('tt.priority', 1);

    // Create another query that joins against the virtual table resulting
    // from the subquery.
    $select = $this->connection
      ->select('test_task', 'tt2');
    $select
      ->addField('tt2', 'task');
    $select
      ->condition('tt2.pid', $subquery, 'IN');

    // The resulting query should be equivalent to:
    // SELECT tt2.name
    // FROM test tt2
    // WHERE tt2.pid IN (SELECT tt.pid AS pid FROM test_task tt WHERE tt.priority=1)
    $people = $select
      ->execute()
      ->fetchCol();
    $this
      ->assertCount(5, $people, 'Returned the correct number of rows.');
  }

  /**
   * Tests we can use a subquery with a relational operator in a WHERE clause.
   */
  public function testConditionSubquerySelect2() {

    // Create a subquery, which is just a normal query object.
    $subquery = $this->connection
      ->select('test', 't2');
    $subquery
      ->addExpression('AVG([t2].[age])');

    // Create another query that adds a clause using the subquery.
    $select = $this->connection
      ->select('test', 't');
    $select
      ->addField('t', 'name');
    $select
      ->condition('t.age', $subquery, '<');

    // The resulting query should be equivalent to:
    // SELECT t.name
    // FROM test t
    // WHERE t.age < (SELECT AVG(t2.age) FROM test t2)
    $people = $select
      ->execute()
      ->fetchCol();
    $this
      ->assertEqualsCanonicalizing([
      'John',
      'Paul',
    ], $people, 'Returned Paul and John.');
  }

  /**
   * Tests we can use 2 subqueries with a relational operator in a WHERE clause.
   */
  public function testConditionSubquerySelect3() {

    // Create subquery 1, which is just a normal query object.
    $subquery1 = $this->connection
      ->select('test_task', 'tt');
    $subquery1
      ->addExpression('AVG([tt].[priority])');
    $subquery1
      ->where('[tt].[pid] = [t].[id]');

    // Create subquery 2, which is just a normal query object.
    $subquery2 = $this->connection
      ->select('test_task', 'tt2');
    $subquery2
      ->addExpression('AVG([tt2].[priority])');

    // Create another query that adds a clause using the subqueries.
    $select = $this->connection
      ->select('test', 't');
    $select
      ->addField('t', 'name');
    $select
      ->condition($subquery1, $subquery2, '>');

    // The resulting query should be equivalent to:
    // SELECT t.name
    // FROM test t
    // WHERE (SELECT AVG(tt.priority) FROM test_task tt WHERE tt.pid = t.id) > (SELECT AVG(tt2.priority) FROM test_task tt2)
    $people = $select
      ->execute()
      ->fetchCol();
    $this
      ->assertEqualsCanonicalizing([
      'John',
    ], $people, 'Returned John.');
  }

  /**
   * Tests that we can use multiple subqueries.
   *
   * This test uses a subquery at the left hand side and multiple subqueries at
   * the right hand side. The test query may not be that logical but that's due
   * to the limited amount of data and tables. 'Valid' use cases do exist :)
   */
  public function testConditionSubquerySelect4() {

    // Create subquery 1, which is just a normal query object.
    $subquery1 = $this->connection
      ->select('test_task', 'tt');
    $subquery1
      ->addExpression('AVG([tt].[priority])');
    $subquery1
      ->where('[tt].[pid] = [t].[id]');

    // Create subquery 2, which is just a normal query object.
    $subquery2 = $this->connection
      ->select('test_task', 'tt2');
    $subquery2
      ->addExpression('MIN([tt2].[priority])');
    $subquery2
      ->where('[tt2].[pid] <> [t].[id]');

    // Create subquery 3, which is just a normal query object.
    $subquery3 = $this->connection
      ->select('test_task', 'tt3');
    $subquery3
      ->addExpression('AVG([tt3].[priority])');
    $subquery3
      ->where('[tt3].[pid] <> [t].[id]');

    // Create another query that adds a clause using the subqueries.
    $select = $this->connection
      ->select('test', 't');
    $select
      ->addField('t', 'name');
    $select
      ->condition($subquery1, [
      $subquery2,
      $subquery3,
    ], 'BETWEEN');

    // The resulting query should be equivalent to:
    // @code
    // SELECT t.name AS name
    // FROM {test} t
    // WHERE (SELECT AVG(tt.priority) AS expression FROM {test_task} tt WHERE (tt.pid = t.id))
    //   BETWEEN (SELECT MIN(tt2.priority) AS expression FROM {test_task} tt2 WHERE (tt2.pid <> t.id))
    //       AND (SELECT AVG(tt3.priority) AS expression FROM {test_task} tt3 WHERE (tt3.pid <> t.id));
    // @endcode
    $people = $select
      ->execute()
      ->fetchCol();
    $this
      ->assertEqualsCanonicalizing([
      'George',
      'Paul',
    ], $people, 'Returned George and Paul.');
  }

  /**
   * Tests that we can use a subquery in a JOIN clause.
   */
  public function testJoinSubquerySelect() {

    // Create a subquery, which is just a normal query object.
    $subquery = $this->connection
      ->select('test_task', 'tt');
    $subquery
      ->addField('tt', 'pid', 'pid');
    $subquery
      ->condition('priority', 1);

    // Create another query that joins against the virtual table resulting
    // from the subquery.
    $select = $this->connection
      ->select('test', 't');
    $select
      ->join($subquery, 'tt', '[t].[id] = [tt].[pid]');
    $select
      ->addField('t', 'name');

    // The resulting query should be equivalent to:
    // @code
    // SELECT t.name
    // FROM test t
    //   INNER JOIN (SELECT tt.pid AS pid FROM test_task tt WHERE priority=1) tt ON t.id=tt.pid
    // @endcode
    $people = $select
      ->execute()
      ->fetchCol();
    $this
      ->assertCount(2, $people, 'Returned the correct number of rows.');
  }

  /**
   * Tests EXISTS subquery conditionals on SELECT statements.
   *
   * We essentially select all rows from the {test} table that have matching
   * rows in the {test_people} table based on the shared name column.
   */
  public function testExistsSubquerySelect() {

    // Put George into {test_people}.
    $this->connection
      ->insert('test_people')
      ->fields([
      'name' => 'George',
      'age' => 27,
      'job' => 'Singer',
    ])
      ->execute();

    // Base query to {test}.
    $query = $this->connection
      ->select('test', 't')
      ->fields('t', [
      'name',
    ]);

    // Subquery to {test_people}.
    $subquery = $this->connection
      ->select('test_people', 'tp')
      ->fields('tp', [
      'name',
    ])
      ->where('[tp].[age] = [t].[age]');
    $query
      ->exists($subquery);
    $result = $query
      ->execute();

    // Ensure that we got the right record.
    $record = $result
      ->fetch();
    $this
      ->assertEquals('George', $record->name, 'Fetched name is correct using EXISTS query.');
  }

  /**
   * Tests NOT EXISTS subquery conditionals on SELECT statements.
   *
   * We essentially select all rows from the {test} table that don't have
   * matching rows in the {test_people} table based on the shared name column.
   */
  public function testNotExistsSubquerySelect() {

    // Put George into {test_people}.
    $this->connection
      ->insert('test_people')
      ->fields([
      'name' => 'George',
      'age' => 27,
      'job' => 'Singer',
    ])
      ->execute();

    // Base query to {test}.
    $query = $this->connection
      ->select('test', 't')
      ->fields('t', [
      'name',
    ]);

    // Subquery to {test_people}.
    $subquery = $this->connection
      ->select('test_people', 'tp')
      ->fields('tp', [
      'name',
    ])
      ->where('[tp].[age] = [t].[age]');
    $query
      ->notExists($subquery);

    // Ensure that we got the right number of records.
    $people = $query
      ->execute()
      ->fetchCol();
    $this
      ->assertCount(3, $people, 'NOT EXISTS query returned the correct results.');
  }

}