Results for “Postgres”
Small, practical examples. Search by task or narrow things down below.
Test missing values with IS NULL
Find rows where an optional value is absent.
IS NULL✓ Tested
Treat an empty trimmed value as missing
SQL: NULLIF converts an empty string to NULL before a fallback is applied.
SQL✓ Tested
Turn a condition into a result label
SQL: Use CASE to describe stock availability for each row.
SQL✓ Tested
Turn known group values into columns
SQL: Conditional aggregation gives a portable pivot when the category set is known.
SQL✓ Tested
Undo a multi-row transfer atomically
SQL: The first transaction commits the fixtures. Rolling back the second transaction restores both sides of the attempted transfer.
SQL✓ Tested
Undo only the work after a savepoint
SQL: After committing the fixtures, roll back a trial change while keeping earlier work in the second transaction.
SQL✓ Tested
Update one matching row
Change a value with an explicit filter.
UPDATE✓ Tested
Update one row using its primary key
SQL: Use a precise WHERE condition to change only the intended row in a scratch table.
SQL✓ Tested
Update rows selected by a related table
SQL: Use EXISTS to limit updates based on an independent eligibility table.
SQL✓ Tested
Update several classifications in one statement
SQL: A CASE expression computes the new value for each row covered by the update predicate.
SQL✓ Tested