python：postgresql：区分大小写的列名

Question

I'm trying to do a select query on a psql DB. But my columnname is "Tagnaam", so case sensitive.

I'm trying this query:

cur.execute("SELECT Tagnaam FROM opc_taginstellingen")

I've read the solution would be to use double quotes on the column name, but that doesn't fix it.

What I also tried:

cur.execute("SELECT "Tagnaam" FROM opc_taginstellingen")
cur.execute("SELECT ""Tagnaam"" FROM opc_taginstellingen")
cur.execute("SELECT '"Tagnaam"' FROM opc_taginstellingen")

None of the above worked.

The error it gives:

    cur.execute("SELECT Tagnaam FROM opc_taginstellingen")
psycopg2.ProgrammingError: column "tagnaam" does not exist
LINE 1: SELECT Tagnaam FROM opc_taginstellingen
               ^

How can I solve this problem?

Thanks in advance.

Answer 1

在查询周围使用"Tagnaam"和单引号（ ' ' ）应该可以：

cur.execute('SELECT "Tagnaam" FROM opc_taginstellingen')

Answer 2

Postgresql and all databases (Oracle, Db2...) usually treat column names in a case-insensitive way, so it should no matter how do you write the field name in the query. Try first all in the psql client. If it works, you can add it to the python code, but be careful, if you use "" inside the string, you should write the string like 'string with "quotedString" inside". The case where the single quotes and double quotes swap can also happen.