我正在编写一个简单的 MySQL 存储过程:

DELIMITER $
DROP PROCEDURE IF EXISTS GetUserByCaseId $
CREATE DEFINER = 'DEV_Organization'@'localhost' 
PROCEDURE GetUserByCaseId (IN searchedForId VARCHAR(8)) 
  LANGUAGE SQL NOT DETERMINISTIC READS SQL DATA SQL SECURITY DEFINER
BEGIN
  SELECT 
    CaseIdAuthenticator.sid AS sid, 
    CaseIdAuthenticator.caseId AS caseId, 
    User.firstName AS firstName, 
    User.lastName AS lastName, 
    User.position AS position, 
    User.email AS email 
  FROM CaseIdAuthenticator
  INNER JOIN User ON User.sid = CaseIdAuthenticator.sid
  WHERE CaseIdAuthenticator.caseId = searchedForId
  LIMIT 1;
END
$

这个有效:

mysql> CALL DEV_Organization.GetUserByCaseId("bro4");
+------+--------+-----------+----------+----------+----------------------+
| sid  | caseId | firstName | lastName | position | email                |
+------+--------+-----------+----------+----------+----------------------+
| 3773 | bro4   | Billy     | O'Neal   |          | billy.oneal@case.edu |
+------+--------+-----------+----------+----------+----------------------+
1 row in set (0.00 sec)

但不幸的是允许客户端通过传递 NULL 逃脱:

mysql> CALL DEV_Organization.GetUserByCaseId(NULL);
Empty set (0.00 sec)

我宁愿让它抛出一个错误。我怎样才能做到这一点？ (简单地设置一个 VARCHAR(8) NOT NULL 的类型会导致 MySQL 在创建过程时抛出错误...)

编辑:评论者询问我的理由。我正在使用 PHP 领域的数据库 API，它看起来像这样:

/**
 * Inside function which is used to implement other procedure functions.
 *
 * @param string $suffix The database schema suffix.
 * @param string $procedure The name of the procedure that should be executed.
 * @param array $arguments A set of arguments which should be passed to the stored procedure.
 * @return PDOStatement The PDOStatement generated by sending the query to the MySQL Server.
 */
private function ProcedureInner($suffix, $procedure, $arguments = array())
{
  $suffix = (string)$suffix;
  $procedure = (string)$procedure;
  $questionMarks = '';
  $args = count($arguments);
  if ($args > 0)
  {
    $questionMarks = '?';
    for ($idx = 1; $idx < $args; ++$idx)
    {
      $questionMarks .= ', ?';
    }
  }
  $stmt = $this->pdo->prepare("CALL `{$this->mode}_{$suffix}`.`{$procedure}` ({$questionMarks})");
  $stmt->execute($arguments);
  return $stmt;
}

/**
 * Executes a stored procedure which returns a single value in a single row.
 *
 * @param string $schema The suffix of the schema where the procedure is located.
 * @param string $procedure The name of the procedure to call.
 * @param array $arguments Arguments to supply to the procedure, if any.
 * @return mixed The content of the value.
 */
public function ProcedureScalar($schema, $procedure, $arguments = array())
{
  $result = $this->ProcedureInner($schema, $procedure, $arguments);
  $answer = $result->fetchColumn(0);
  $result->closeCursor();
  return $answer;
}

请注意客户端很容易忘记在参数数组中传递参数。然而，这是数据库抽象的低级部分，我不想在此处设置寻找特定参数的约束。

最佳答案

MySQL 5.5 及更高版本提供 SIGNAL仅出于此目的(在用户例程中引发任意异常):

....
BEGIN
  IF searchedForId IS NULL THEN
    SIGNAL SQLSTATE '45000' -- unhandled user-defined exception
      SET MESSAGE_TEXT = 'Parameter may not be NULL';
  END IF;
  SELECT 
    CaseIdAuthenticator.sid AS sid, 
....

关于mysql - 如何防止存储过程的用户传递 null？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8252159/