MySQL LIMIT on DELETE statement

问题:

I put together a test table for a error I recently came across. It involves the use of LIMIT when attempting to delete a single record from a MySQL table.

The error I speak of is "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LIMIT 1' at line 1"

The table I put together is called test; it has 3 columns, id, name and created. I populated the table with several records and then attempted to delete one. Below is the statement I used to try and accomplish this.

DELETE t FROM test t WHERE t.name = 'foo' LIMIT 1

Without the use of LIMIT 1, the statement executes just fine, but of course I wouldn't be using LIMIT if there wasn't a need for it.

I'm fully aware that I can use another statement to accomplish this DELETE successfully. See below: DELETE FROM test WHERE name = 'foo' LIMIT 1

However my question is centered on why the first statement isn't working with LIMIT.

So my question is, what I have done incorrectly with respect to the first statement to generate this error?

回答1:

the delete query only allows for modifiers after the DELETE 'command' to tell the database what/how do handle things.

see this page

回答2:

simply use

DELETE FROM test WHERE 1= 1 LIMIT 10 

回答3:

DELETE t.* FROM test t WHERE t.name = 'foo' LIMIT 1

@Andre If I understood what you are asking, I think the only thing missing is the t.* before FROM.

回答4:

Use row_count - your_desired_offset

So if we had 10 rows and want to offset 3

 10 - 3 = 7

Now the query delete from table where this = that order asc limit 7 keeps the last 3, and order desc to keep the first 3:

$row_count - $offset = $limit

Delete from table where entry = criteria order by ts asc limit $limit

回答5:

First I struggled a bit with a DELETE FROM ... USING ... WHERE query,... Since i wanted to test first so i tried with SELECT FROM ... USING... WHERE ... and this caused an error , ... Then i wanted to reduce the number of deletions adding
LIMIT 10 which also produced an error Then i removed the "LIMIT" and - hurray - it worked: "1867 rows deleted. (Query took 1.3025 seconds.)"

The query was:

DELETE FROM tableX 
USING tableX , tableX as Dup 
WHERE NOT tableX .id = Dup.id 
 AND tableX .id > Dup.id 
 AND tableX .email= Dup.email 
 AND tableX .mobil = Dup.mobil

This worked.