触发器在不应该发出消息时引发消息

Question

我有一个附加到表的触发器，当某些列组合不唯一时应该引发异常。

CREATE TRIGGER uniqueness BEFORE INSERT ON a
  BEGIN
    SELECT RAISE(FAIL, 'Record is not unique !')
    FROM a
    WHERE ((NEW.st <> 1) 
      AND (p = NEW.p)
      AND ((name = NEW.name) OR (safe_name = NEW.safe_name)));
  END;

但它似乎有时会在不必要的时候被触发。

例如，如果 safe_name 是 foo5，并且存在具有 safe_name foo-5 的现有记录。但是foo5 != foo-5 那么为什么会这样呢？

================================================ ===============

好吧，我知道为什么会这样了。这是您在 PHP 中重现它的方法：

$pdo = new PDO('sqlite::memory:');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);      
$pdo->sqliteCreateCollation('NS', 'strnatcasecmp');      

$pdo->query('CREATE TABLE a(
   id INTEGER PRIMARY KEY AUTOINCREMENT,
   st INTEGER NOT NULL,
   p  INTEGER NOT NULL,
   name TEXT NOT NULL COLLATE NS,
   safe_name NOT NULL COLLATE NS)');

$pdo->query('CREATE TRIGGER uniqueness BEFORE INSERT ON a
  BEGIN
    SELECT RAISE(FAIL, "Record is not unique !")
    FROM a
    WHERE ((NEW.st <> 1) 
      AND (p = NEW.p)
      AND ((name = NEW.name) OR (safe_name = NEW.safe_name)));
  END;');

// success
$pdo->query('INSERT INTO a(st, p, name, safe_name) VALUES(2, 2, "Foo 5", "foo-5")');

// fail :(
$pdo->query('INSERT INTO a(st, p, name, safe_name) VALUES(2, 2, "foo  5", "foo5")');

当排序规则处于活动状态时，Foo 5 名称显然等于 foo 5。

如果我删除 sqliteCreateCollation 调用和 COLLATE NS 语句，它会起作用：/

是否有任何解决方案可以让我保留整理功能？我只需要它来订购，但显然它也用于比较......

Answer 1

您应该能够保留排序规则，但仅将其切换为二进制以用于触发器查询。

$pdo = new PDO('sqlite::memory:');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);      
$pdo->sqliteCreateCollation('NS', 'strnatcasecmp');      

$pdo->query('CREATE TABLE a(
   id INTEGER PRIMARY KEY AUTOINCREMENT,
   st INTEGER NOT NULL,
   p  INTEGER NOT NULL,
   name TEXT NOT NULL COLLATE NS,
   safe_name NOT NULL COLLATE NS)');

$pdo->query('CREATE TRIGGER uniqueness BEFORE INSERT ON a
  BEGIN
    SELECT RAISE(FAIL, "Record is not unique !")
    FROM a
    WHERE ((NEW.st <> 1) 
      AND (p = NEW.p)
      AND ((name COLLATE BINARY = NEW.name) OR (safe_name COLLATE BINARY = NEW.safe_name)));
  END;');

// success
$pdo->query('INSERT INTO a(st, p, name, safe_name) VALUES(2, 2, "Foo 5", "foo-5")');

// should work now
$pdo->query('INSERT INTO a(st, p, name, safe_name) VALUES(2, 2, "foo  5", "foo5")');

Answer 2

您已专门设置排序规则以进行不区分大小写的比较。尝试将其更改为：

$pdo->sqliteCreateCollation('NS', 'strnatcmp');

看看有没有帮助。