Lets a query read a value from a later row of its own results, avoiding the need to join the table to itself.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains LEAD in context, with comparison tables and the common traps.
Terms in this definition
- CRUD
Shorthand for create, read, update and delete, the four basic things you do with data. Data-plane roles in Azure Cosmos DB, for instance, authorise those operations on items.
- JOIN
Combines rows from two or more tables in one SELECT, most often by pairing a primary key with the foreign key that refers to it.
- Event
Table in Log Analytics where entries from Windows event logs are kept.
Related terms
- CFD
An Azure Boards chart showing how many work items sit in each state over time, revealing flow, work in progress and bottlenecks. It can't give precise lead or cycle times; separate widgets do that.
- Compliance review
A structured check, led by a Lead Enterprise Architect with set procedures and checklists, of whether a project conforms to the architecture. Its report is signed off by the Architecture Board and the customer.
- Requirements Impact Assessment
A deliverable judging what effect new information has on existing requirements, naming the phases to revisit and the one that takes the lead on prioritising.
- RESPECT NULLS
The default behaviour of LAG, LEAD, FIRST_VALUE and LAST_VALUE, in which NULLs are counted. Its opposite, IGNORE NULLS, skips them, which is handy for carrying the last known value forward.
- Stable tag
An image tag, for example :1.0, that keeps being updated and reused, which suits base images. Using one for deployments can lead to nodes running different images.
- WIP limit
A soft maximum on how many items a board column should hold. Once it is exceeded, Azure Boards turns the column's count red; more work in progress means longer lead and cycle times.