Results for “EXISTS”
Small, practical examples. Search by task or narrow things down below.
Delete rows selected by a related table
Postgres: A correlated EXISTS limits the delete to explicitly listed records.
Postgres✓ Tested
Delete rows selected by a related table
SQLite: A correlated EXISTS limits the delete to explicitly listed records.
SQLite✓ Tested
Find records without any related rows
SQL: NOT EXISTS avoids the NULL pitfalls of NOT IN when the subquery column can be missing.
SQL✓ Tested
Find records without any related rows
SQL Server: NOT EXISTS avoids the NULL pitfalls of NOT IN when the subquery column can be missing.
SQL Server✓ Tested
Find records without any related rows
Postgres: NOT EXISTS avoids the NULL pitfalls of NOT IN when the subquery column can be missing.
Postgres✓ Tested
Find records without any related rows
SQLite: NOT EXISTS avoids the NULL pitfalls of NOT IN when the subquery column can be missing.
SQLite✓ Tested
Group records by a field
Python: Accumulate related values with defaultdict without checking whether each group exists.
Python✓ Tested
Insert only keys absent from a destination
SQL: NOT EXISTS supports a set-based missing-row insert in a single-writer example.
SQL✓ Tested
Insert only keys absent from a destination
SQL Server: NOT EXISTS supports a set-based missing-row insert in a single-writer example.
SQL Server✓ 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 only keys absent from a destination
SQLite: NOT EXISTS supports a set-based missing-row insert in a single-writer example.
SQLite✓ Tested
Name an intermediate query with a CTE
Make a filtered result reusable within one statement.
CTE✓ Tested