DAY_IN_WEEK — Return Numeric Day of Week
Returns a numeric weekday indicator for a supplied date and is commonly used in older ABAP reports and scheduling helpers. It answers only the day-of-week question; it does not know plant holidays, shift patterns, factory calendars, or whether an application considers that date available for processing.
Verified-reference draft for DAY_IN_WEEK, focused on real input/output semantics, edge cases, S/4HANA implications, and safe use. The page deliberately avoids inventing release-specific exception names; the active SE37 signature remains the authority for exact technical typing.
Published 20 Sept 2026· 651 words
What it does
Returns a numeric weekday indicator for a supplied date and is commonly used in older ABAP reports and scheduling helpers. It answers only the day-of-week question; it does not know plant holidays, shift patterns, factory calendars, or whether an application considers that date available for processing. The function should be treated as one technical building block inside a larger business process. It does not replace application-specific validation, authorization, posting-period control, or master-data checks unless its own documentation explicitly says those are part of the service.
Important parameters
ERPClimb documents the parameters that materially affect the result rather than reproducing the entire SE37 signature. Always inspect the active interface before coding because optional flags and exact DDIC types can differ across releases.
- DATE is the principal input and a weekday number is returned; document the numbering convention used by the caller.
- Keep source and target values typed with the DDIC elements expected by the interface so conversion, decimal, language, and length rules are preserved.
- If the function returns both a result and supporting factor/rate/calendar metadata, keep them together when troubleshooting so the result can be reproduced.
Exceptions
Treat technical exceptions and 'no matching customizing/data' outcomes separately. A clean SY-SUBRC does not excuse the caller from validating that the result is present and meaningful for the business context.
- Invalid dates and hard-coded assumptions about which number represents Monday or Sunday are the primary risks.
- Where named exceptions are not stated here, use SE37 function documentation as the authoritative list instead of copying exception names from an unrelated release.
- Log enough input context to reproduce the failure without writing sensitive business data unnecessarily.
How to call it safely
Normalize the input with the field's assigned conversion semantics, call the function with explicit date/language/unit/currency context, check exceptions immediately, and validate the result before continuing. For bulk processing, avoid repeated calls when the same calendar, rate, or metadata can be resolved once and cached safely within the current LUW.
ECC vs S/4HANA
It remains available in S/4HANA classic ABAP, although modern code may use built-in date/time APIs and factory-calendar services when workdays matter. Availability in classic S/4HANA does not by itself make the function a released ABAP Cloud API. For new clean-core work, prefer released CDS conversion functions, classes, or business APIs where SAP provides an equivalent.
Common pitfalls
- Do not assume the function's existence means it is a released clean-core API; verify release status in the target system.
- Use DDIC-typed variables rather than hard-coded character lengths so S/4HANA length extensions and language-dependent formats do not get truncated.
- Handle all declared exceptions and validate the semantic result before using it in a posting, interface, or calculation.
- Test boundary cases such as blank values, end-of-month dates, leap years, missing customizing, and maximum field lengths relevant to the function.
- Do not confuse formatting/conversion with business determination: the caller still owns which calendar, rate type, unit, language, or target format is correct for the scenario.
Whose problem this is
ABAP development owns correct typing, exception handling, and call context. Functional ownership depends on the data being interpreted: Finance owns exchange-rate and currency rules, MM/PP owns material and unit semantics, HCM owns statutory date logic, and Basis or cross-application configuration owners maintain central calendars and units.
Related SAP objects
Reviewed pages this object connects to in the ERPClimb knowledge graph.
Source: ERPClimb — https://erpclimb.com/sap-function-modules/day-in-weekERPClimb is an independent platform and is not affiliated with SAP SE. Reference pages are written and reviewed by SAP consultants for learning and troubleshooting.