Why is this, how come sometimes it gets an error, sometimes not

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You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near

What I have tried:

function edit_post_no_img($id,$title,$contents,$category,$slug,$tags,$description){
		$result = $this->db->query("UPDATE tbl_post SET post_title='$title',post_description='$description',post_contents='$contents',post_last_update=NOW(),post_category_id='$category',post_tags='$tags',post_slug='$slug' WHERE post_id='$id'");
		return $result;
	}

Posted 29-Dec-20 3:41am

Member 15033100

Updated 29-Dec-20 4:01am

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2 solutions

Solution 2

Why are you getting the error somethines, and not others? Simple: you are doing DB access very wrong - and it's a lot more dangerous than "it fails sometimes". Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

Posted 29-Dec-20 4:01am

OriginalGriff

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Sandeep Mewara · Accepted Answer · 2020-12-29T03:57:00

This kind of errors arise when you have used incorrect syntax.

Debug and you should be able to see the query formed. Correct the query and it should solve it.

One of the values in below query seems empty.

SQL

"UPDATE 
   tbl_post 
SET  
   post_title='$title',
   post_description='$description',
   post_contents='$contents',
   post_last_update=NOW(),
   post_category_id='$category',
   post_tags='$tags',
   post_slug='$slug' 
WHERE 
   post_id='$id'"

Based on the details on their knowledge base: Basic SQL Debugging - MariaDB Knowledge Base[^]

Quote:
ERROR 1064: You have an error in your SQL syntax; check the manual that corresponds to your
MariaDB server version for the right syntax to use near ' ' at line 1

The empty ' ' can be disheartening. Clearly there is an error, but where? A good place to look is at the end of the query. The ' ' suggests that the parser reached the end of the statement while still expecting some syntax token to appear.

Check for missing closers, such as ' and ):

SQL

SELECT * FROM someTable WHERE field = 'value

Look for incomplete clauses, often indicated by an exposed comma:

SQL

SELECT * FROM someTable WHERE field = 1 GROUP BY id,

PS: Generally, you should always make use of Parameterized query to avoid SQL Injection. Read about protecting from SQL Injection here: SQL Injection Mitigation: Using Parameterized Queries[^]