如何根据条件插入？

Question

我有这些INSERT查询：

$db->prepare("INSERT INTO
              events (post_id, table_code, other_id, user_id, author_id, date_time )
              VALUES (?      , 15        , ?       , ?      , ?        , UNIX_TIMESTAMP()),
                     (?      , 15        , ?       , ?      , ?        , UNIX_TIMESTAMP())
")->execute(array($answer_id, $answer_id, $author_ques_id, $author_ques_id,
                  $answer_id, $answer_id, $author_ques_id, $author_ans_id));

如您所见，上面的查询在events表中插入了两行。 现在，我需要在第二行的路上加一个条件。 我的意思是，如果$condition为true，则插入第二行，否则不应插入第二行。 （始终应插入第一行） 。

注意： $condition始终包含布尔值。

好吧，如何在第二行插入的方式上放置该条件？

Answer 1

您可以使用以下insert select语句：

$db
->prepare("INSERT INTO
             events (post_id, table_code, other_id, user_id, author_id, date_time )
             select ?, 15, ?, ?, ?, UNIX_TIMESTAMP()
              UNION ALL
             select ?, 15, ?, ?, ?, UNIX_TIMESTAMP()
               from (select 1) as a
              where 1=?
")->execute(array($answer_id, $answer_id, $author_ques_id, $author_ques_id,
                  $answer_id, $answer_id, $author_ques_id, $author_ans_id,
                  ($yourCondition?1:0) ));

Answer 2

由于$ condition是一个php变量，为什么不这样在PHP中这样做：

if ($condition === true) {
    $db->prepare($first_and_seccond_row);
} else {
    $db->prepare($first_row);
}

Answer 3

在2个查询中这样做有什么问题？

$query = $db->prepare("INSERT INTO
              events (post_id, table_code, other_id, user_id, author_id, date_time)
              VALUES (?, 15, ?, ?, ?, UNIX_TIMESTAMP())");

$query->execute(array($answer_id1, $answer_id1, $author_ques_id1, $author_ans_id1));

if ($condition)
    $query->execute(array($answer_id2, $answer_id2, $author_ques_id2, $author_ans_id2));

Answer 4

您可以在准备和执行之前构建查询字符串和值数组。

$query = "INSERT INTO
          events (post_id, table_code, other_id, user_id, author_id, date_time )
          VALUES (?, 15, ?, ?, ?, UNIX_TIMESTAMP())";
$values = array($answer_id, $answer_id, $author_ques_id, $author_ques_id);
if ($condition) {
    $query .= ",(?, 15, ?, ?, ?, UNIX_TIMESTAMP())";
    $values = array_merge($values, array($answer_id, $answer_id, $author_ques_id, $author_ans_id);
}
$db->prepare($query)->execute($values);