Query a dataset applying filter on month and year in PostgreSQL

I have the following dataset

CREATE TABLE my_table
( the_debt_id varchar(6) NOT NULL, the_debt_paid date NOT NULL, the_debt_due date NOT NULL
)
INSERT INTO my_table
VALUES ('LMUS01', '2019-05-03', '2019-05-02'), ('LMUS01', '2019-06-03', '2019-06-02'), ('LMUS01', '2019-07-01', '2019-07-02'), ('LMUS02', '2019-05-03', '2019-05-07'), ('LMUS02', '2019-06-07', '2019-06-07')

And I want to query this dataset by filtering only the rows where the_debt_paid is in June 2019.

The expected result is:

the_debt_id the_debt_paid the_debt_due
LMUS01 2019-06-03 2019-06-02
LMUS02 2019-06-07 2019-06-07

I tried the following:

SELECT * FROM my_table
WHERE EXTRACT(month, the_debt_paid) = 6

But I don't know how apply with the year which is 2019. Any help will be greatly appreciated.

2 Answers

Try this:

SELECT * FROM my_table
WHERE EXTRACT('month' from the_debt_paid) = 6
and EXTRACT('year' from the_debt_paid)=2019

You can write your query like this also:

SELECT * FROM my_table
WHERE (EXTRACT(month from the_debt_paid), EXTRACT('year' from the_debt_paid))=(6,2019)

you can compare month and year by using extractDEMO

Use direct date comparisons!

SELECT *
FROM my_table
WHERE the_debt_paid >= '2019-06-01' AND the_debt_paid < '2019-07-01';

Using functions on dates is bad from multiple perspectives.

• First, it is less readable. I find that explicit date constants are more easily understood and maintained over time.
• Second, it prevents the use of indexes on the columns, in almost all cases.
• Third, it makes the query much harder to optimize, because statistics on the expression are not as accurate as statistics on the column itself.