我可以在 PHP 中使用 DECLARE 作为 SQL 语句吗

Question

I am trying to execute a query in PHP, but this code wouldn't work for some reason, it doesn't detect the keywords at all(DECLARE, SELECT, WHERE). Is there anything I can do and after all can I even use DECLARE in PHP as a mySQLi statement.

$sql2 ="DECLARE @MaxID INT; SELECT @MaxID = MAX(productID) FROM products; UPDATE sunglasses SET sunglassesId = @MaxID WHERE sunglassesId = 0;";

After all I am trying to update a field in Table1 where its initial value is 0 with a value from a field in Table2. Hope that made sense.

PS tried this query in Microsoft SQL Management studio and it worked, in PHP it doesnt.

Answer 1

change your query to this and you don't need any other variable:

UPDATE sunglasses 
SET sunglassesId = (SELECT MAX(productID) FROM products)
WHERE sunglassesId = 0;