SQL glossary: Journeyman level
20 SQL terms at the Journeyman level, each with a short definition and a link to its full page.
Updated
- Alias
- An Alias is an alternate (usually short) name assigned to a table to make it easier to…
- COMMIT
- A statement that successfully ends a transaction and makes its changes durable.
- Common Table Expression (CTE)
- A named query expression introduced by WITH for use within one statement.
- Correlated Subquery
- A subquery that refers to values from an outer query and is evaluated in that context.
- DENSE_RANK
- A window function assigning equal rank to peers without leaving gaps after ties.
- LAG
- A window function returning a value from an earlier row in the window partition.
- LEAD
- A window function returning a value from a later row in the window partition.
- OVER Clause
- The clause defining the row window used by a window function.
- PARTITION BY
- An OVER subclause dividing query rows into independent window-function groups.
- RANK
- A window function assigning equal rank to peers and leaving gaps after ties.
- READ COMMITTED
- An isolation level preventing a statement from reading uncommitted changes.
- READ UNCOMMITTED
- The isolation level allowing the broadest concurrency and permitting dirty reads.
- Recursive CTE
- A CTE that repeatedly refers to its own accumulated result until no new rows are produced.
- REPEATABLE READ
- An isolation level preventing reread rows from changing during the transaction.
- ROLLBACK
- A statement that reverses a transaction's uncommitted changes.
- ROW_NUMBER
- A window function assigning consecutive numbers to rows within each window partition.
- SAVEPOINT
- A named point inside a transaction to which later work can be rolled back.
- SERIALIZABLE
- The strongest standard isolation level, requiring results consistent with some serial order.
- Window Frame
- The subset of rows around the current row used by a window function.
- Window Function
- A function calculating across related rows without collapsing them into one row per group.