select.inc

<?php

/**
 * @file
 * Select builder for DB2 database engine.
 */

/**
 * @ingroup database
 * @{
 */

class SelectQuery_ibm extends SelectQuery {

  public function __toString() {
    // For convenience, we compile the query ourselves if the caller forgot
    // to do it. This allows constructs like "(string) $query" to work. When
    // the query will be executed, it will be recompiled using the proper
    // placeholder generator anyway.
    if (!$this->compiled()) {
      $this->compile($this->connection, $this);
    }

    // Create a sanitized comment string to prepend to the query.
    $comments = $this->connection->makeComment($this->comments);

    // SELECT
    $query = $comments . 'SELECT ';
    if ($this->distinct) {
      $query .= 'DISTINCT ';
    }

    // FIELDS and EXPRESSIONS
    $fields = array();
    foreach ($this->tables as $alias => $table) {
      if (!empty($table['all_fields'])) {
        $fields[] = $this->connection->escapeTable($alias) . '.*';
      }
    }
    foreach ($this->fields as $alias => $field) {
      // Always use the AS keyword for field aliases, as some
      // databases require it (e.g., DB2).
      $fields[] = (isset($field['table']) ? $this->connection->escapeTable($field['table']) . '.' : '') .  $this->connection->escapeField($field['field']) . ' AS ' . $this->connection->escapeAlias($field['alias']);
    }
    foreach ($this->expressions as $alias => $expression) {
      $fields[] = $expression['expression'] . ' AS ' . $this->connection->escapeAlias($expression['alias']);
    }
    $query .= implode(', ', $fields);


    // FROM - We presume all queries have a FROM, as any query that doesn't won't need the query builder anyway.
    $query .= "\nFROM ";
    foreach ($this->tables as $alias => $table) {
      $query .= "\n";
      if (isset($table['join type'])) {
        $query .= $table['join type'] . ' JOIN ';
      }

      // If the table is a subquery, compile it and integrate it into this query.
      if ($table['table'] instanceof SelectQueryInterface) {
        // Run preparation steps on this sub-query before converting to string.
        $subquery = $table['table'];
        $subquery->preExecute();
        $table_string = '(' . (string) $subquery . ')';
      }
      else {
        $table_string = '{' . $this->connection->escapeTable($table['table']) . '}';
      }

      // Don't use the AS keyword for table aliases, as some
      // databases don't support it (e.g., DB2).
      $query .=  $table_string . ' ' . $this->connection->escapeTable($table['alias']);

      if (!empty($table['condition'])) {
        $query .= ' ON ' . $table['condition'];
      }
    }

    // WHERE
    if (count($this->where)) {
      // There is an implicit string cast on $this->condition.
      $query .= "\nWHERE " . $this->where;
    }

    // GROUP BY
    if ($this->group) {
      $query .= "\nGROUP BY " . implode(', ', $this->group);
    }

    // HAVING
    if (count($this->having)) {
      // There is an implicit string cast on $this->having.
      $query .= "\nHAVING " . $this->having;
    }

    // ORDER BY
    if ($this->order) {
      $query .= "\nORDER BY ";
      $fields = array();
      foreach ($this->order as $field => $direction) {
        $fields[] = $field . ' ' . $direction;
      }
      $query .= implode(', ', $fields);
    }

    // UNION is a little odd, as the select queries to combine are passed into
    // this query, but syntactically they all end up on the same level.
    if ($this->union) {
      foreach ($this->union as $union) {
        $query .= ' ' . $union['type'] . ' ' . (string) $union['query'];
      }
    }

    if ($this->forUpdate) {
      $query .= ' FOR UPDATE';
    }

    // RANGE
    // DB2 is using a different range syntax than all other else
    // core-supported database, which rewrite the entire query structure, so
    // we need to override this method with alternate logic as LAST STEP.
    if (!empty($this->range)) {
      $query = 'SELECT * FROM (SELECT SUB1.*, ROWNUM AS ' . OCI_RANGE_ROWNUM_PLACEHOLDER . ' FROM (' . $query . ') SUB1) WHERE ' . OCI_RANGE_ROWNUM_PLACEHOLDER . ' BETWEEN ' . ((int) $this->range['start'] + 1) . ' AND ' . ((int) $this->range['start'] + (int) $this->range['length']);
    }

    return $query;
  }

  public function groupBy($field) {
    // DB2 don't allow GROUP BY with field alias, use original name.
    $this->group[$field] = isset($this->fields[$field]['field']) ? $this->fields[$field]['field'] : $field;
    return $this;
  }
}

/**
 * @} End of "ingroup database".
 */