Query just one row that meet three conditions in SQL - sql

Question

I'd like to make a query that returns just one row when it meets 3 conditions. I have a database that looks like this:
Location
Date
Item
Price
Chicago
2021-06-10
1
150
New York
2021-06-10
2
130
Chicago
2021-06-10
1
150
Los Angeles
2021-06-10
3
100
Atlanta
2021-06-10
4
120
New York
2021-06-09
2
125
Chicago
2021-06-09
1
155
Los Angeles
2021-06-09
3
99
Atlanta
2021-06-09
4
140
This database contains the price of different items, by date and location. This price changes each day and the price in each location for the same item does not need to be the same. Given that this database contains each sale made in a day, for each item, I'd like to make a query that returns only one observation by Location, Date and Item. I want to have like a time series for each the price of each item, in each location. So the resulting table should look like this:
Location
Date
Item
Price
Chicago
2021-06-10
1
150
New York
2021-06-10
2
130
Los Angeles
2021-06-10
3
100
Atlanta
2021-06-10
4
120
New York
2021-06-09
2
125
Chicago
2021-06-09
1
155
Los Angeles
2021-06-09
3
99
Atlanta
2021-06-09
4
140
Hope someone can help me, thanks.

Answer 1

To elaborate on the comments, this will give exactly what you have specified.
SELECT
DISTINCT
*
FROM
yourTable
The DISTINCT key word looks at all columns in each row and eliminates any row that exactly matches any other row.
If the price can vary within a day, but you want the maximum value, for example, use a GROUP BY...
SELECT
location,
date,
item,
MAX(price) AS max_price
FROM
yourTable
GROUP BY
location,
date,
item
That will ensure you get one row per unique combination of location, date, item, and then you can pick which price to include using aggregate functions.
Note: Using keywords such as date as column names is a bad idea. depending on your database you may need to "quote"/"escape" such column names, and even then the make reading the code harder for others.