When formatting a number in php, pay attention to the number range.

Compare to construct SQL statements
Copy codeThe Code is as follows:
$ SQL = 'select *
FROM sdb_comments
WHERE goods_id = '. intval ($ goods_id ).'
AND for_comment_id IS NULL
AND object_type = ". $ item ."
AND disabled = "false"
AND display = "true "';

I prefer to do this:
Copy codeThe Code is as follows:
$ SQL = sprintf ('select *
FROM sdb_comments
WHERE goods_id = %. 0f
AND for_comment_id IS NULL
AND object_type = "% s"
AND disabled = "false"
AND display = "true" ', (float) $ goods_id, $ item );

This statement is still simple. If it is more complex, concatenating strings is a nightmare.

The second method is more convenient, but a small problem: when formatting a number, you need to pay attention to its value range. Numeric operation. The SQL statement returned at the end is not what we need.

I made a summary today:

% D: 2 ^ 31 ~ 2 ^ 31-1 (-2147483648 ~ 2147483647) (convert int to signed decimal)

% B: binary (convert int type to binary)

% C: character (convert int type to character)

% U: 2 ^ 32-1 (0 ~ 4294967295) (convert int to signed decimal)

% F:-2 ^ 128-(-3.4E38 ~ + 3.4E38) (convert float to float) Localization

% F:-2 ^ 128-(-3.4E38 ~ + 3.4E38) (convert float to float) Non-localization

% O (convert int to octal)

% S: String

% X: converts an int into a hexadecimal string of lowercase letters.

% X: hexadecimal format for converting an int to an uppercase letter

Because the id in the database may be large. If % d is used, the correct result may not be returned because it is out of the range. Therefore, it is recommended that %. 0f be better than % d When formatting the id.