Engineering Atlas
☰ Menu
PortfolioAtlasDeploySQLData ViewsEnvBites
PT
Engineering Atlas / Snippets / Explicit Column Contract — No SELECT *
sfmc // SQLPRODUCTION

Explicit Column Contract — No SELECT *

Promote production queries with explicit output columns instead of SELECT *.

sqlselect starschemamigration
Context Pack →Open Workspace →
Trust & provenancePRODUCTION
Evidence tierPRODUCTIONOfficial sources1Other sources0Last verified2026-10-05

Evidence tier describes my hands-on relationship with the content. Official sources describe platform contracts/documentation. Production observations should not automatically be treated as official limits.

EvidencePRODUCTION
Difficultyfoundation
Verified2026-10-05
Use when

A query becomes a durable automation dependency.

Preparing assets for migration or schema review.

SELECT
    SubscriberKey,
    EmailAddress,
    Status,
    ModifiedDate
FROM [Customer_Source]
Why it works

Explicit columns make the query output contract visible and resilient to unrelated source-field changes.

Operational notes

Salesforce also documents that JOIN + SELECT * is not permitted in Query Activities.

Related
Stage Before Large Add/Update

Move expensive transformation into an overwrite staging DE before a large Add/Update write.

→
Connected knowledge

Keep following the context.

Explicit and inferred relationships from the Atlas model.

View this node in graph →
SnippetDIRECT LINK
Stage Before Large Add/Update

Move expensive transformation into an overwrite staging DE before a large Add/Update write.

Explicit related snippet
SQL GuideDIRECT LINK
Stage Large Queries Instead of Being Clever

When one Query Activity has too many joins, scans and transformations, split the work into deterministic stages. You gain observability, smaller scans and easier failure isolation.

Guide → snippet
SQL GuideDIRECT LINK
ORDER BY Is Not a Storage Contract

A Data Extension is a relational table, not an ordered list. ORDER BY is useful when paired with TOP or window functions to select which rows win, but downstream consumers should never rely on physical row order.

Guide → snippet
Pattern
Explicit SELECT Lists

Name the columns you intend to move instead of depending on SELECT *.

Shared context: schema, migration
Pattern
SELECT * in Production Automations

Convenient during exploration, fragile as a durable data contract.

Shared context: select star, schema
Sources / verification
Salesforce — SQL Reference ↗