SQL Error [42601]: ERROR: syntax error at or near “limit”

All we need is an easy explanation of the problem, so here it is.

when I am using this command to update table in PostgreSQL 13:

UPDATE rss_sub_source 
SET sub_url = SUBSTRING(sub_url, 1, CHAR_LENGTH(sub_url) - 1) 
WHERE sub_url LIKE '%/'
limit 10

but shows this error:

SQL Error [42601]: ERROR: syntax error at or near "limit"
  Position: 111

why would this error happen and what should I do to fix it?

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

LIMIT isn’t a valid keyword in an UPDATE statement according to the official PostgreSQL documentation:

[ WITH [ RECURSIVE ] with_query [, ...] ]
UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ]
    SET { column_name = { expression | DEFAULT } |
          ( column_name [, ...] ) = [ ROW ] ( { expression | DEFAULT } [, ...] ) |
          ( column_name [, ...] ) = ( sub-SELECT )
        } [, ...]
    [ FROM from_item [, ...] ]
    [ WHERE condition | WHERE CURRENT OF cursor_name ]
    [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]

Reference: UPDATE (PostgreSQL Documentation )

Solution

Remove LIMIT 10 from your statement.

Method 2

You could make something like this

But a Limit without an ORDER BY makes no sense, so you must choose one that gets you the correct 10 rows

UPDATE rss_sub_source t1
SET t1.sub_url = SUBSTRING(t1.sub_url, 1, CHAR_LENGTH(t1.sub_url) - 1) 
FROM (SELECT id FROM rss_sub_source WHERE sub_url LIKE '%/' ORDER BY id LIMIT 10) t2 
WHERE t2.id = t1.id

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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