Results for “Schema design & transactions”
Small, practical examples. Search by task or narrow things down below.
Treat an empty trimmed value as missing
SQLite: NULLIF converts an empty string to NULL before a fallback is applied.
SQLite✓ Tested
Turn a condition into a result label
Postgres: Use CASE to describe stock availability for each row.
Postgres✓ Tested
Turn known group values into columns
SQL: Conditional aggregation gives a portable pivot when the category set is known.
SQL✓ Tested
Turn known group values into columns
SQL Server: Conditional aggregation gives a portable pivot when the category set is known.
SQL Server✓ Tested
Turn known group values into columns
Postgres: Conditional aggregation gives a portable pivot when the category set is known.
Postgres✓ Tested
Turn known group values into columns
SQLite: Conditional aggregation gives a portable pivot when the category set is known.
SQLite✓ Tested
Update one row using its primary key
Postgres: Use a precise WHERE condition to change only the intended row in a scratch table.
Postgres✓ Tested
Update rows selected by a related table
SQL: Use EXISTS to limit updates based on an independent eligibility table.
SQL✓ Tested
Update rows selected by a related table
SQL Server: Use EXISTS to limit updates based on an independent eligibility table.
SQL Server✓ Tested
Update rows selected by a related table
Postgres: Use EXISTS to limit updates based on an independent eligibility table.
Postgres✓ Tested
Update rows selected by a related table
SQLite: Use EXISTS to limit updates based on an independent eligibility table.
SQLite✓ 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