postgresql - PostgreSQL : what are simple quotation marks for?

Question

How could I remove simple quotation marks that appear in empty cells? See image below

The columns can be either TEXT or CHARACTER VARYING(), these signs are still present. I have other tables with no quotation marks in empty cells... The extract above is the result of an importation of an ORACLE table into my PGSQL database. This is probably the reason why.

Answer 1

我猜是导入过程引入了单引号。如果此查询解决了它

select num_position, replace(num_position, '''', '')
from t;

然后替换所有单引号

update t
set
    num_position = replace(num_position, '''', ''),
    num_plan = replace(num_plan, '''', '')