Comparisons Sub-Select Issues

Started by Brian C. Doyleover 24 years ago2 messagesgeneral
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#1Brian C. Doyle
bcdoyle@mindspring.com

Hello,

How would I do a comparison sub select ie
select this where that>=(*select something where whatever='exactly');

Currently if I try to run a query in this format I get nothing back but if
i remove the > I get an exact match which I do not want

Can I do this???

#2Jason Earl
jdearl@yahoo.com
In reply to: Brian C. Doyle (#1)
Re: Comparisons Sub-Select Issues

I do queries of this sort all of the time. If I used
the following script to create a couple of tables:

--BEGIN SQL script--
DROP TABLE birthdays;
DROP TABLE key_dates;

BEGIN;

CREATE TABLE birthdays (
username varchar(20) PRIMARY KEY,
dt date
);

INSERT INTO birthdays (username, dt) VALUES ('jason',
'1971-10-14');
INSERT INTO birthdays (username, dt) VALUES
('kaelynn', '1976-02-29');
INSERT INTO birthdays (username, dt) VALUES
('brooklyn', '1999-01-19');
INSERT INTO birthdays (username, dt) VALUES
('zachary', '2001-05-05');

CREATE TABLE key_dates (
name varchar(20) PRIMARY KEY,
dt date
);

INSERT INTO key_dates (name, dt) VALUES ('first date',
'1997-02-15');
INSERT INTO key_dates (name, dt) VALUES
('anniversary', '1997-05-10');
INSERT INTO key_dates (name, dt) VALUES ('Y2K',
'2000-01-01');

COMMIT;
--END SQL script--

I could then query the database like so:

processdata=> SELECT * FROM birthdays WHERE dt >=
(SELECT dt FROM key_dates WHERE name = 'first date');
username | dt
----------+------------
brooklyn | 1999-01-19
zachary | 2001-05-05
(2 rows)

In fact, this works with all kinds of values. If this
doesn't work for you then you have a serious problem
with your installation of PostgreSQL.

Or, more likely, I have simply misunderstood what your
problem is...

Hope this is helpful,
Jason

--- "Brian C. Doyle" <bcdoyle@mindspring.com> wrote:

Hello,

How would I do a comparison sub select ie
select this where that>=(*select something where
whatever='exactly');

Currently if I try to run a query in this format I
get nothing back but if
i remove the > I get an exact match which I do not
want

Can I do this???

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