Results for “SQL”
Small, practical examples. Search by task or narrow things down below.
Generate numbers with a recursive CTE
Build a bounded sequence using SQL recursion.
recursive CTE✓ Tested
Get the latest row in each group
Select one ordered row per key with DISTINCT ON.
DISTINCT ON✓ Tested
Give a result column a readable name
Postgres: Use AS to label a computed result column.
Postgres✓ Tested
Group by more than one field
Postgres: Each distinct combination of grouping fields produces its own row.
Postgres✓ Tested
Include every row tied for the highest score
Postgres: Compare with MAX rather than limiting to an arbitrary number of rows.
Postgres✓ Tested
Include missing values in a not-equal filter
Postgres: Ordinary inequality does not include NULL; explicitly include it when that is the intended rule.
Postgres✓ Tested
Include zero counts for missing relationships
Postgres: Count the non-null child key after a left join so a missing relationship produces zero.
Postgres✓ Tested
Increment a stored value in the database
Postgres: An in-database arithmetic update avoids a separate application read-modify-write step.
Postgres✓ Tested
Insert a row with named columns
Add a record without relying on implicit column order.
INSERT✓ Tested
Insert only keys absent from a destination
Postgres: NOT EXISTS supports a set-based missing-row insert in a single-writer example.
Postgres✓ Tested
Insert or update on a key conflict
Use a unique key to update an existing row.
ON CONFLICT✓ Tested
Inspect deleted rows
Return values from the rows a DELETE removes.
DELETE✓ Tested