PostgreSQL, Npgsql returning 42601: syntax error at or near “$1”

Question

I\'m trying to use Npgsql and/or Dapper to query a table and I keep running into Npgsql.PostgresException 42601: syntax error at or near \"$1\".

Here is

Answer 1

To subtract days from a date (assuming log_date is data type date), you can simplify:

"SELECT * FROM logs.logs WHERE log_date > CURRENT_DATE - @days;"

And provide @days as unquoted numeric literal (digits only) - which is taken to be an integer. This is even more efficient, since date - integer returns date, while date - interval returns timestamp.

The manual about interval input.

Answer 2

PostgreSQL doesn't allow you to stick a parameter anywhere in a query. What you want can be achieved with the following:

var command = new NpgsqlCommand("select * from Logs.Logs where Log_Date > current_date - @days", conn))
command.Parameters.AddWithValue("@days", TimeSpan.FromDays(days));

This way you're passing the interval directly from Npgsql to PostgreSQL, rather than a part of the expression designed to create that interval.

Answer 3

i got this error using DapperExtensions

adding

DapperExtensions.DapperExtensions.SqlDialect = new PostgreSqlDialect();
DapperAsyncExtensions.SqlDialect = new PostgreSqlDialect();

before creating the connection fixed the issue