SOQL Date Functions

This skill activates when a query needs to group or filter records by a date period — pulling the year, quarter, month, week, day, or hour out of a Date or DateTime field inside SOQL instead of reading every row into Apex and bucketing them by hand. The mechanism is the family of SOQL date functions (CALENDAR_YEAR(), FISCAL_QUARTER(), DAY_ONLY(), and ten more). They are one of the seven function categories in the SOQL SELECT reference, alongside aggregate functions, convertCurrency(), convertTimezone(), FORMAT(), GROUPING(), and toLabel().

---

Before Starting

Gather this context before working on anything in this domain:

• Know whether you are grouping or just filtering. Both are valid. A date function can appear in a WHERE clause to filter results even when the query has no GROUP BY clause at all (e.g. WHERE CALENDAR_YEAR(CloseDate) = 2026). It does not force you into aggregation.
• Know the field type. Most date functions take a Date or DateTime field. Two of them — DAY_ONLY() and HOUR_IN_DAY() — accept only a DateTime field. Pointing them at a Date field is a query error.
• Know the org's fiscal-year configuration. FISCAL_MONTH(), FISCAL_QUARTER(), and FISCAL_YEAR() are not supported when the org has custom (generic) fiscal years enabled. If the org uses custom fiscal periods, these functions are unavailable and you must group by calendar periods or a formula field instead.
• Remember the time-zone basis. SOQL returns DateTime values as UTC. Date functions bucket on that raw UTC instant unless you wrap the field in convertTimezone(), so a record created at 11pm local can land in the "next day" bucket. See apex/timezone-and-datetime-pitfalls for the full treatment.

---

Core Concepts

The 13 date functions

Each returns a number except DAY_ONLY(), which returns a Date:

Function	Returns	Input	Notes
CALENDAR_MONTH(field)	Number (1–12)	Date/DateTime	Calendar month
CALENDAR_QUARTER(field)	Number (1–4)	Date/DateTime	Calendar quarter
CALENDAR_YEAR(field)	Number	Date/DateTime	Calendar year
DAY_IN_MONTH(field)	Number	Date/DateTime	Day of month
DAY_IN_WEEK(field)	Number	Date/DateTime	Day of week
DAY_IN_YEAR(field)	Number	Date/DateTime	Day of year
DAY_ONLY(field)	Date	DateTime only	Date portion of a DateTime
FISCAL_MONTH(field)	Number	Date/DateTime	Not supported with custom fiscal years
FISCAL_QUARTER(field)	Number	Date/DateTime	Not supported with custom fiscal years
FISCAL_YEAR(field)	Number	Date/DateTime	Not supported with custom fiscal years
HOUR_IN_DAY(field)	Number (0–23)	DateTime only	Hour of day
WEEK_IN_MONTH(field)	Number	Date/DateTime	Ordinal week within the month
WEEK_IN_YEAR(field)	Number	Date/DateTime	Ordinal week within the year

Two placements: filter (WHERE) and group (SELECT + GROUP BY)

A date function has two independent jobs:

• Filter — put it in the WHERE clause to keep only rows in a period. This works with no GROUP BY:

  SELECT Id, Amount FROM Opportunity WHERE CALENDAR_YEAR(CloseDate) = 2026
  

• Group — put it in SELECT alongside an aggregate to bucket rows. When a date function appears in SELECT, it must also appear in GROUP BY:

  SELECT CALENDAR_YEAR(CloseDate) yr, SUM(Amount) total
  FROM Opportunity
  GROUP BY CALENDAR_YEAR(CloseDate)
  

The date-literal comparison rule

A date function returns a number (or, for DAY_ONLY(), a Date). You cannot compare the result of a date function to a date literal in a WHERE clause. Compare to an integer instead:

-- CORRECT: compare to an integer
WHERE CALENDAR_YEAR(CloseDate) = 2026

-- WRONG: compare to a date literal (ISO date or relative literal)
WHERE CALENDAR_YEAR(CloseDate) = 2026-01-01
WHERE CALENDAR_MONTH(CloseDate) = THIS_MONTH

If your intent is a relative window (this fiscal year, last 90 days), you likely want a date literal on the raw field — WHERE CloseDate = THIS_FISCAL_YEAR — not a date function at all. That is a literal, not a function; it is out of scope here.

---

Common Patterns

Pattern: database-side period rollup

When to use: you need a total/count per year, quarter, or month and today you SELECT all rows and sum them in an Apex loop.

How it works: move the bucketing into SOQL with a date function in SELECT + GROUP BY, and read the results from AggregateResult:

for (AggregateResult ar : [
        SELECT CALENDAR_QUARTER(CloseDate) qtr, SUM(Amount) total
        FROM Opportunity
        WHERE CloseDate = THIS_YEAR
        GROUP BY CALENDAR_QUARTER(CloseDate)]) {
    Integer quarter = (Integer) ar.get('qtr');
    Decimal total   = (Decimal) ar.get('total');
}

Why not the alternative: iterating every Opportunity to bucket by quarter pulls unbounded rows into heap and burns query rows; the grouped query returns one row per quarter and does the arithmetic in the database. See apex/apex-aggregate-queries for the AggregateResult/GROUP BY mechanics.

Pattern: period filter without aggregation

When to use: you just want the rows in a period (a fixed calendar year, a specific fiscal quarter) and no rollup.

How it works: put the date function in WHERE only — no GROUP BY needed:

SELECT Id, Name, Amount FROM Opportunity WHERE FISCAL_QUARTER(CloseDate) = 3

Why not the alternative: people reach for a CloseDate >= :start AND CloseDate < :end range and hand-compute the boundaries. FISCAL_QUARTER(CloseDate) = 3 reads intent directly and follows the org's fiscal calendar — but only when standard fiscal years are in effect (see Gotchas).

Pattern: collapse a DateTime to a date bucket

When to use: you have a DateTime field (e.g. CreatedDate) and want to count per calendar day.

How it works: DAY_ONLY() strips the time and yields a Date you can group on:

SELECT DAY_ONLY(CreatedDate) d, COUNT(Id) c
FROM Case
GROUP BY DAY_ONLY(CreatedDate)

Why not the alternative: grouping on the raw DateTime produces one bucket per distinct instant (useless); DAY_ONLY() is dateTime-only and returns the date part so each calendar day is one row.

---

Decision Guidance

Situation	Recommended Approach	Reason
Keep only rows in a period, no rollup	Date function in WHERE, no GROUP BY	A date function filters without requiring aggregation
Total/count per period	Date function in SELECT and GROUP BY	A SELECT date function must appear in GROUP BY
"This year / last 90 days" relative window	Date literal on the raw field (WHERE CloseDate = THIS_YEAR)	Literals express rolling windows; a date function returns a number, not a window
Org has custom fiscal years enabled	Group by calendar functions or a fiscal formula field	FISCAL_* functions are unsupported under custom fiscal years
Need the date part of a DateTime	DAY_ONLY(dateTimeField)	Returns a Date; accepts only a DateTime field
Need hour-of-day distribution	HOUR_IN_DAY(dateTimeField)	Hour component; accepts only a DateTime field
Buckets must follow the user's local day	Wrap in convertTimezone(field) before the date function	SOQL evaluates the raw UTC instant otherwise

---

Recommended Workflow

1. Classify the need — filtering a period (→ WHERE only), rolling up per period (→ SELECT + GROUP BY), or a relative rolling window (→ a date literal, which is out of scope for this skill).
2. Pick the function by period and field type — calendar vs. fiscal; year/quarter/month/week/day/hour. Confirm the field is a DateTime before choosing DAY_ONLY() or HOUR_IN_DAY().
3. Check fiscal configuration — if you chose a FISCAL_* function, confirm the org does not have custom fiscal years enabled; if it does, switch to calendar functions or a fiscal formula field.
4. Write the clause correctly — compare a date-function result to an integer, never a date literal; if the function is in SELECT, repeat it verbatim in GROUP BY.
5. Decide time-zone basis — if buckets must follow local days rather than UTC, wrap the field in convertTimezone().
6. Validate — run scripts/check_soql_date_functions.py --query "<your SOQL>" (or --manifest-dir over a source tree) to catch date-literal comparisons and SELECT-without-GROUP BY mistakes.

---

Review Checklist

Run through these before marking work in this area complete:

• Every date function in SELECT also appears, unchanged, in GROUP BY
• No date-function result is compared to a date literal (ISO YYYY-MM-DD or a relative literal) in WHERE
• DAY_ONLY() / HOUR_IN_DAY() are applied only to DateTime fields, not Date fields
• FISCAL_MONTH/QUARTER/YEAR are not used if the org has custom fiscal years enabled
• Time-zone intent is explicit — convertTimezone() wraps the field where local-day bucketing matters
• A relative window ("this year", "last N days") uses a date literal on the raw field, not a date function

---

Salesforce-Specific Gotchas

Non-obvious platform behaviors that cause real production problems:

1. Comparing to a date literal is rejected — WHERE CALENDAR_YEAR(CloseDate) = 2026-01-01 fails; the function yields a number, so compare to the integer 2026. This surfaces at query compile time and often confuses developers who mix up date functions with date literals.
2. FISCAL_* silently unavailable under custom fiscal years — enabling custom (generic) fiscal years disables FISCAL_MONTH/QUARTER/YEAR. Code that worked in one org throws in another purely because of that org setting, not the query.
3. DAY_ONLY() / HOUR_IN_DAY() are DateTime-only — pointing them at a Date field (or a formula returning Date) errors; they exist specifically to extract from a DateTime.
4. UTC bucketing skews the "day" — date functions read the raw UTC value, so late-evening local records fall into the next UTC day/month/quarter unless you wrap the field in convertTimezone().

---

Output Artifacts

Artifact	Description
A grouped SOQL query	SELECT <dateFn>(field), <aggregate> ... GROUP BY <dateFn>(field) for period rollups read via AggregateResult
A filtered SOQL query	WHERE <dateFn>(field) = <integer> for period filtering with no aggregation
scripts/check_soql_date_functions.py output	A report of date-literal comparisons, SELECT-without-GROUP BY, and misspelled-function issues in your SOQL

---

Related Skills

• apex/apex-aggregate-queries — owns the GROUP BY / ROLLUP / CUBE / HAVING / AggregateResult mechanics that date-function grouping plugs into; use it for the aggregation side.
• apex/timezone-and-datetime-pitfalls — the UTC-vs-local-day nuance and convertTimezone() usage that decides which bucket a record lands in.
• apex/soql-fundamentals — base SOQL clause structure, and SOQL relative date literals (TODAY, LAST_N_DAYS:n, THIS_FISCAL_YEAR), which are literals, not the functions this skill covers.
• apex/soql-format-function-localization — FORMAT() for localized display of the numbers/dates these functions return.