Reference

SQL SELECT Statement Syntax

The shape of a query, the order you write its clauses, and the order the database actually runs them.

A SELECT query reads rows from one or more tables and returns a result set. You write the clauses in a fixed order, even though the database evaluates them in a different order.

Full shape

select   column_a, column_b, count(*)
from     some_table
where    column_a > 0          -- filter rows
group by column_a, column_b    -- collapse into groups
having   count(*) > 5          -- filter groups
order by count(*) desc         -- sort the result
limit    10                    -- keep the first N rows

Clauses

Clause	Purpose
`SELECT`	Which columns or expressions to return.
`FROM`	Which table(s) to read, including joins.
`WHERE`	Keep only rows that match a condition (before grouping).
`GROUP BY`	Collapse rows into one row per group.
`HAVING`	Keep only groups that match a condition (after grouping).
`ORDER BY`	Sort the final result.
`LIMIT`	Return at most N rows.

Logical evaluation order

Knowing this order explains a lot of beginner surprises. For example, it explains why you cannot use a SELECT alias in WHERE, but you can in ORDER BY.

FROM / joins
WHERE
GROUP BY
HAVING
SELECT (aliases are created here)
ORDER BY
LIMIT

Columns, aliases, and DISTINCT

Example

select distinct
       category_id,
       product_name as name,
       price * 0.9   as sale_price
from   products
order by sale_price desc

* returns every column. That is handy while exploring, but name the columns you need in real queries. DISTINCT removes duplicate rows from the result. AS renames a column in the output.

Dialect note

DuckDB lets you reference a SELECT alias in WHEREand GROUP BY as a convenience. Most other engines (Postgres, SQL Server) do not. Repeat the full expression there to stay portable.

Lesson

What Is SQL?

Understand tables, rows, columns, and queries.

Lesson

Tables, Rows, and Columns in SQL

Learn the basic shape of relational data.

Lesson

Meet the SQL Workbench

Run queries and read results in the browser.

Lesson

Your First SQL SELECT Statement

Write a first SELECT and read the returned rows.