Question

I am retrieving the following sql statement from a table and then using bind variables to substitute the values in. I get a syntax error when running the statement. It seems to be occurring as a result of the lower() function however I believe I am using this correctly. I have tried running the statement manually via psql and it works fine with the values I provide. Does anyone have any ideas on this one? I have tried switching the ‘ for $$ but this had no effect.

statement

SELECT column_name 
FROM information_schema.columns 
WHERE table_name=lower(':1') 
  and column_name=lower(':2')

expected basic statement with substituted values

SELECT column_name 
FROM information_schema.columns 
WHERE table_name=lower('MyTableName') 
  and column_name=lower('MyColumnName')

statement run by postgresql

SELECT column_name 
FROM information_schema.columns 
WHERE table_name=lower('((E'RWOL_TMA_ROADWORKS'))') 
and column_name=lower('((E'TPHS_CWAY_RESTRICT_TYPE'))')

Error in C#

ERROR: 42601: syntax error at or near \"MyTableName\"

Error in PostgreSQL log file

2012-04-16 11:36:15 BST ERROR:  syntax error at or near "RWOL_TMA_ROADWORKS" at character 80
2012-04-16 11:36:15 BST STATEMENT:  SELECT column_name FROM information_schema.columns WHERE table_name=lower('((E'RWOL_TMA_ROADWORKS'))') and column_name=lower('((E'TPHS_CWAY_RESTRICT_TYPE'))')

EDIT: Retrieval and implementation code is written in C#. I use the database connection base classes and the npgsql provider factory in order to make connections, run queries and retrieve the data. This method works for all other queries that use this method of binding variables etc apart from this one where I try to use the lower() function.

EDIT: I have tried removing the quotes altogether to let the binding agent deal with quoting the values and this provided the same syntax error.

EDIT: Have now enabled logging and added the actual statement that postgresql is running.

Answer 1

I think vyegorov is on the right path – there’s something funny with your placeholders.

I don’t think your second example is the actual query after substition because that doesn’t contain any errors. Where did it come from and why aren’t you providing the actual query – do you have statement logging turned on in PostgreSQL?

Also, I’m suspicious of the syntax error – what’s going on with the escaped double-quotes? Are they actually double-quotes and not doubled-up single quotes?

1. Are you sure you need single-quotes around your placeholders? Usually the drivers manage that for you.

2. Are you sure you aren’t double-quoting the values anywhere?

Get the actual SQL and look at the quoting and the problem will be obvious I suspect.

UPDATE: now have SQL

Here’s the error in the posted statement:

lower('((E'RWOL_TMA_ROADWORKS'))')

You’ve got two levels of quotes here. Remove the ones you’ve added and we should end up with something like:

lower((E'RWOL_TMA_ROADWORKS'))

Ignoring the repeated brackets that’s valid (The E’…’ is the syntax for a c-style escaped string – google around standard_conforming_strings).