测试是否已存在某些内容(Testing if something already exists)

测试是否已存在某些内容(Testing if something already exists)

我正在努力为我的课程学习更多的分数，我的老师说这会有所帮助。 在创建变量或表等时，我想知道如何对其进行编码，以便如果它已经存在则不会运行代码。

$sql2 = "CREATE TABLE referee(refereeID INT (5) NOT NULL PRIMARY KEY AUTO_INCREMENT, name VARCHAR(20))"; if (mysqli_query($link, $sql)){ echo "Table created successfully"; } else { echo "ERROR: Could not able to execute $sql. " . mysqli_error($link); }

I am trying to pick up a few more marks for my coursework and my teacher said that this will help. When creating a variable or table etc, I want to know how I can code it so that if it already exists it doesn't run the code.

$sql2 = "CREATE TABLE referee(refereeID INT (5) NOT NULL PRIMARY KEY AUTO_INCREMENT, name VARCHAR(20))"; if (mysqli_query($link, $sql)){ echo "Table created successfully"; } else { echo "ERROR: Could not able to execute $sql. " . mysqli_error($link); }

最满意答案

您可以尝试使用此查询

$sql = "CREATE TABLE IF NOT EXISTS `referee` ( `refereeID` int(11) NOT NULL auto_increment, `name` varchar(255) NOT NULL default '', PRIMARY KEY (`refereeID`) )";

这将检查是否有任何这样的表在数据库中。

希望这可以帮助。

You can try with this query

$sql = "CREATE TABLE IF NOT EXISTS `referee` ( `refereeID` int(11) NOT NULL auto_increment, `name` varchar(255) NOT NULL default '', PRIMARY KEY (`refereeID`) )";

This checks to see if any table like this is in the database.

Hope this helps.