Postgres 查询无法根据列值找到行

Question

I want to select rows based on a column value. I know for a fact the column value exists. The first query returns 100 rows from the listing table. The second query, which looks for listings.OriginatingSystemName = 'mfrmls` returns nothing. Why?

(Removing the quotes or using double quotes does not work).

I am using pgAdmin4 to run these queries.

first query:

select * from listing limit 100;

second query:

select * from listing where 'listing.OriginatingSystemName' = 'mfrmls'

This produces a 'column does not exist' error:

select * from listing where OriginatingSystemName = 'mfrmls'

Answer 1

The correct syntax is to just write the column name in your WHERE statement:

SELECT * FROM listings WHERE "OriginatingSystemName" = 'mfrmls';

To elaborate further:

What your original query is doing is selecting every row in the listings table where the text string 'listings.OriginatingSystemName' is equal to this other text string 'mfrmls'. It is not actually grabbing the value from the column you want. No row in the table satisfies your where statement because your where statement is always false. Therefore, no rows are returned but the query was a success.

We need to implement the double quotes when dealing with case-sensitive identifiers. Here is some helpful documentation .