Results for “SQL”
Small, practical examples. Search by task or narrow things down below.
Filter rows before grouping
SQLite: WHERE limits the rows contributing to the aggregate; it differs from filtering completed groups with HAVING.
SQLite✓ Tested
Find missing values with IS NULL
SQL: Use IS NULL rather than equality to test for missing data.
SQL✓ Tested
Find missing values with IS NULL
SQL Server: Use IS NULL rather than equality to test for missing data.
SQL Server✓ Tested
Find missing values with IS NULL
SQLite: Use IS NULL rather than equality to test for missing data.
SQLite✓ Tested
Find parents whose every child meets a rule
SQL: Combine existence with the absence of a violating child to exclude parents with no children.
SQL✓ Tested
Find parents whose every child meets a rule
SQL Server: Combine existence with the absence of a violating child to exclude parents with no children.
SQL Server✓ Tested
Find parents whose every child meets a rule
SQLite: Combine existence with the absence of a violating child to exclude parents with no children.
SQLite✓ Tested
Find parents with at least two child rows
SQL: Use a correlated count when testing a per-parent threshold.
SQL✓ Tested
Find parents with at least two child rows
SQL Server: Use a correlated count when testing a per-parent threshold.
SQL Server✓ Tested
Find parents with at least two child rows
SQLite: Use a correlated count when testing a per-parent threshold.
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