public function Schema::addUniqueKey in Drupal driver for SQL Server and SQL Azure 3.0.x

Same name and namespace in other branches

1. 8.2 drivers/lib/Drupal/Driver/Database/sqlsrv/Schema.php \Drupal\Driver\Database\sqlsrv\Schema::addUniqueKey()
2. 8 drivers/lib/Drupal/Driver/Database/sqlsrv/Schema.php \Drupal\Driver\Database\sqlsrv\Schema::addUniqueKey()

Add a unique key.

Parameters

$table: The table to be altered.

$name: The name of the key.

$fields: An array of field names.

Throws

\Drupal\Core\Database\SchemaObjectDoesNotExistException If the specified table doesn't exist.

\Drupal\Core\Database\SchemaObjectExistsException If the specified table already has a key by that name.

Overrides Schema::addUniqueKey

2 calls to Schema::addUniqueKey()

Schema::createTable in drivers/lib/Drupal/Driver/Database/sqlsrv/Schema.php

Create a new table from a Drupal table definition.

Schema::recreateTableKeys in drivers/lib/Drupal/Driver/Database/sqlsrv/Schema.php

Re-create keys associated to a table.

File

drivers/lib/Drupal/Driver/Database/sqlsrv/Schema.php, line 474

Class

Schema

Namespace

Drupal\Driver\Database\sqlsrv

Code

public function addUniqueKey($table, $name, $fields) {
  if (!$this
    ->tableExists($table)) {
    throw new SchemaObjectDoesNotExistException(t("Cannot add unique key %name to table %table: table doesn't exist.", [
      '%table' => $table,
      '%name' => $name,
    ]));
  }
  if ($this
    ->uniqueKeyExists($table, $name)) {
    throw new SchemaObjectExistsException(t("Cannot add unique key %name to table %table: unique key already exists.", [
      '%table' => $table,
      '%name' => $name,
    ]));
  }
  $this
    ->createTechnicalPrimaryColumn($table);

  // Then, build a expression based on the columns.
  $column_expression = [];
  foreach ($fields as $field) {
    if (is_array($field)) {
      $column_expression[] = 'SUBSTRING(CAST(' . $field[0] . ' AS varbinary(max)),1,' . $field[1] . ')';
    }
    else {
      $column_expression[] = 'CAST(' . $field . ' AS varbinary(max))';
    }
  }
  $column_expression = implode(' + ', $column_expression);

  // Build a computed column based on the expression that replaces NULL
  // values with the globally unique identifier generated previously.
  // This is (very) unlikely to result in a collision with any actual value
  // in the columns of the unique key.
  $this->connection
    ->query("ALTER TABLE {{$table}} ADD __unique_{$name} AS CAST(HashBytes('MD4', COALESCE({$column_expression}, CAST(" . self::TECHNICAL_PK_COLUMN_NAME . " AS varbinary(max)))) AS varbinary(16))");
  $this->connection
    ->query("CREATE UNIQUE INDEX {$name}_unique ON {{$table}} (__unique_{$name})");
  $this
    ->resetColumnInformation($table);
}