PostgreSQL_Notes

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Sorting Records

We use the ORDER BY keyword to sort our query results.
The default order will be ASCENDING
To change the order you can apply an optional keyword DESC (short for descending) after the column which wish to order by:

We can order by character as well as by number.
We can apply a second ordering rule, the first will be given priority.
- The second will be followed when two entries are equal.

We can use a column to order by, but we can also use a calculation to order by.
- For Example: price / weight
OFFSET - Any time we want to skip some number of records within a result set.
LIMIT - will constrain the number of records we get back from a query.
- LIMIT 1 will give you the most or least of some result.
Combining LIMIT and ORDER BY
- We can do things like get the 5 least expensive products by combining the two
Combining LIMIT, ORDER BY and OFFSET
- We can do things like get the 4 most expensive under the very most expensive product by combining all three
- LIMIT goes before OFFSET

Combining LIMIT and OFFSET
- We can combine offset and limit to decrease the size of our result set.
- If we have 1000s of results we would not want to return the entire result set, we would want to return only some limited number of those results at a time.
  - We can also keep track of where our offset is incase we wish to request more of those results.