stmt_init() seems to clear previous (possibly erroneous) results on the DB connection, which means you don't necessarily need to use it but it could make the code more robust.
In a PHPUnit test, I had a sequence of prepared queries on the same connection. One of them fetched a row from a SELECT but didn't keep fetching until it drained the connection, so it left some stale results. When the next query did this:
<?php
$db = $this->getConnection()->getDbConnection();
$preparedQuery = $db->prepare ($query);
?>
the prepare() call generated an error: "Could not prepare query: Commands out of sync; you can't run this command now." Changing to this:
<?php
$db = $this->getConnection()->getDbConnection();
$preparedQuery = $db->stmt_init();
$preparedQuery->prepare ($query);
?>
resolved the problem.
mysqli::stmt_init
mysqli_stmt_init
(PHP 5, PHP 7, PHP 8)
mysqli::stmt_init -- mysqli_stmt_init — 初始化语句并返回用于 mysqli_stmt_prepare（调用）的对象
说明
面向对象风格
过程化风格
分配并初始化适合 mysqli_stmt_prepare() 的语句对象。
注意:
在调用 mysqli_stmt_prepare() 之前，对其它 mysqli_stmt 函数的后续调用都会失败。
返回值
返回对象。
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User Contributed Notes 2 notes
Jeff C ¶
8 years ago
mamdo7 at hotmail dot com ¶
10 years ago
you can use $stmt = $mysqli->prepare(); directly without stmt-init() . i think there is no need for stmt-init .
