Syntax errors are quite common while coding.
But, things go for a toss when it results in website errors.
PostgreSQL error 42601 also occurs due to syntax errors in the database queries.
At Bobcares, we often get requests from PostgreSQL users to fix errors as part of our Server Management Services.
Today, let’s check PostgreSQL error in detail and see how our Support Engineers fix it for the customers.
What causes error 42601 in PostgreSQL?
PostgreSQL is an advanced database engine. It is popular for its extensive features and ability to handle complex database situations.
Applications like Instagram, Facebook, Apple, etc rely on the PostgreSQL database.
But what causes error 42601?
PostgreSQL error codes consist of five characters. The first two characters denote the class of errors. And the remaining three characters indicate a specific condition within that class.
Here, 42 in 42601 represent the class “Syntax Error or Access Rule Violation“.
In short, this error mainly occurs due to the syntax errors in the queries executed. A typical error shows up as:
Here, the syntax error has occurred in position 119 near the value “parents” in the query.
How we fix the error?
Now let’s see how our PostgreSQL engineers resolve this error efficiently.
Recently, one of our customers contacted us with this error. He tried to execute the following code,
CREATE OR REPLACE FUNCTION prc_tst_bulk(sql text)
RETURNS TABLE (name text, rowcount integer) AS
$$
BEGIN
WITH m_ty_person AS (return query execute sql)
select name, count(*) from m_ty_person where name like '%a%' group by name
union
select name, count(*) from m_ty_person where gender = 1 group by name;
END
$$ LANGUAGE plpgsql;
But, this ended up in PostgreSQL error 42601. And he got the following error message,
ERROR: syntax error at or near "return"
LINE 5: WITH m_ty_person AS (return query execute sql)
Our PostgreSQL Engineers checked the issue and found out the syntax error. The statement in Line 5 was a mix of plain and dynamic SQL. In general, the PostgreSQL query should be either fully dynamic or plain. Therefore, we changed the code as,
RETURN QUERY EXECUTE '
WITH m_ty_person AS (' || sql || $x$)
SELECT name, count(*)::int FROM m_ty_person WHERE name LIKE '%a%' GROUP BY name
UNION
SELECT name, count(*)::int FROM m_ty_person WHERE gender = 1 GROUP BY name$x$;
This resolved the error 42601, and the code worked fine.
[Need more assistance to solve PostgreSQL error 42601?- We’ll help you.]
Conclusion
In short, PostgreSQL error 42601 occurs due to the syntax errors in the code. Today, in this write-up, we have discussed how our Support Engineers fixed this error for our customers.
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var google_conversion_label = «owonCMyG5nEQ0aD71QM»;
Last tested: Feb 2021
Overview
This SQL error generally means that somewhere in the query, there is invalid syntax.
Some common examples:
- Using a database-specific SQL for the wrong database (eg BigQuery supports DATE_ADD, but Redshift supports DATEADD)
- Typo in the SQL (missing comma, misspelled word, etc)
- Missing a sql clause (missed from, join, select, etc)
- An object does not exist in the database or is not accessible from the current query (eg referencing orders.id when there is no orders table joined in the current query, etc)
In some circumstances, the database error message may display extra detail about where the error was raised, which can be helpful in narrowing down where to look.
Error Message
SQL ERROR: syntax error at or near
Troubleshooting
This should generally be the first step to troubleshoot any SQL syntax error in a large query: iteratively comment out blocks of SQL to narrow down where the problem is.
TIP: To make this process easier, change the group by clause to use position references
eg: group by 1,2,3,4,5 instead of group by orders.status, orders.date, to_char(...)...
as well as separate the where and having clauses onto multiple lines.
So for example, say we have the following query:
play_arrow
WITH cte AS (
select id, status, sales_amountfrom orders
)
select status, foo.date, sum(cte.sales_amount), count(*) from cte
join foo on cte.date = foo.date
group by status, foo.date
order by 3 desc
We could start by running just the portion in the CTE:
play_arrow
-- WITH cte AS (
select id, status, sales_amountfrom orders
-- )
-- select status, foo.date, sum(cte.sales_amount), count(*)
-- from cte
-- join foo on cte.date = foo.date
-- group by 1, 2
-- order by 3 desc
Then strip out the aggregates and portions related to them
play_arrow
WITH cte AS (
select id, status, sales_amountfrom orders
)
select status, foo.date, -- sum(cte.sales_amount), count(*)
from cte
join foo on cte.date = foo.date
-- group by 1, 2
-- order by 3 desc
Iteratively stripping out / adding back in portions of the query until you find the minimum query to trigger the error.
-
Lookup functions and syntax If the query is small enough, or if we’ve narrowed the scope enough with 1, google all the functions used in the query and verify that they exist and are being used correctly.
-
Verify all objects exist Verify that you’ve joined all tables used in the select, where, and having clause, and that those tables exist in the db. Once we’ve narrowed things down from 1, also check that each column exists in the table specified.
Introduction
Actually, this article has a relation with the existence of the previous article. That previous article exist in this link with the title of ‘How to Solve Error Message Model Attribute Problem SyntaxError: invalid syntax in Django Application’. It is actually just inappropriate format of the column name available in the SQL file. That SQL file actually containing an INSERT statement for restoring data to the targeted database. But since there is a column name which is not following the standard rule which starts with a character that is not number or letter, it cause the restore process to fail.
The following is just to describe that accessing the database is not the cause of the problem.
Microsoft Windows [Version 10.0.19042.1288] (c) Microsoft Corporation. All rights reserved. C:UsersPersonal>cd C:>psql -Upostgres -d db_app Password for user postgres: psql (14.0) WARNING: Console code page (437) differs from Windows code page (1252) 8-bit characters might not work correctly. See psql reference page "Notes for Windows users" for details. Type "help" for help. db_app=# q
After that, the process for inserting records by importing it or restoring it using the following command exist as follows :
C:>psql -Uuser_app -d db_app < "C:UsersPersonalDownloadsinsert-current-product.sql" Password for user db_user: ERROR: syntax error at or near "[" LINE 1: ...,[product_code... ^
As in the above command execution, it fail with an error message appear.
Solution
Actually, the solution for the above error message causing it is because of the column’s character is not a proper name for a column name. In that case, just change it into a proper one. So, edit the SQL file and find the column’s character or the column name which is the cause for the database restore process to fail. Changing the column name from [product_code] to another proper one. That new column name is ‘product_code’. After editing the file, just execute the process for importing or restoring the data once more as follows :
C:>psql -Uuser_sinergi -d db_sinergi < "C:UsersPersonalDownloadsinsert-current-product.sql" Password for user db_user: INSERT 0 556 C:>
Fortunately, the process is a success as in the output of the command above.
Yeah, I think it would be handy for sure. I have a few thoughts…
However it ends up it should be pretty clear about being intended for when you cannot add parameters to a query in a normal way. I think having to manually escape your inputs with hand-rolled string concatenation when they cannot be parameterized is a pain and error prone, but I don’t want it to be confused as a general purpose substitute for parameterized queries.
So I’m wondering if, like you said, it could be it’s own module. Something like pg-escape
and you could use it like…
var escape = require('pg-escape') client.query(escape('create user ? with password Something`, ['my_username']))
I used the ?
placeholder from mysql there instead of the PostgreSQL $n
placeholder because that might advertise it more as something that’s not happening within the PostgreSQL server itself? Not sure…maybe that’s ugly? Another advantage of it being it’s own module is it could contain a lovely readme file that explained something like «Generally you wanna use parameterized SQL, but sometimes commands don’t take parameters where you want. You can use this to safely escape those commands» or something.
Of course it could also just be added onto the query or client object as another method. My only hesitation with that is this module already has a lot of functionality, as you’ve probably noticed. I’m actually working right now in spinning parts of it out into other modules for better reuse and to hopefully lower the barrier of entry for collaboration. It it were stuck onto the client object it could look like this maybe…
var text = client.escape('create user $1 with password Something', ['my_username']) client.query(text, function(err, rows) { })
or if the client-side escaping used the question mark placeholder you could get crazy:
var text = client.escape('select ? from my_table where id = $1', ['my_column_name']) client.query(text, ['some_id'], function(err, rows) { });
What do you think?