Merge pull request #3407 from dolthub/angela/yeardiff

Calculate `year` for `timestampdiff` based on date and clock time values

Author: angelamayxie

enginetest/queries/function_queries.go

@@ -911,7 +911,31 @@ var FunctionQueryTests = []QueryTest{
 		Query:    "SELECT TIMESTAMPDIFF(SECOND, null, '2007-12-31 00:00:00');",
 		Expected: []sql.Row{{nil}},
 	},
-
+	// https://github.com/dolthub/dolt/issues/10393
+	{
+		Query:    "SELECT TIMESTAMPDIFF(YEAR, DATE '2011-07-05', DATE '2026-07-04')",
+		Expected: []sql.Row{{14}},
+	},
+	{
+		Query:    "SELECT TIMESTAMPDIFF(YEAR, DATE '2026-07-04', DATE '2011-07-05')",
+		Expected: []sql.Row{{-14}},
+	},
+	{
+		Query:    "SELECT TIMESTAMPDIFF(YEAR, DATE '2026-07-05', DATE '2026-07-04')",
+		Expected: []sql.Row{{0}},
+	},
+	{
+		Query:    "SELECT TIMESTAMPDIFF(YEAR, DATE '2026-07-04', DATE '2026-07-05')",
+		Expected: []sql.Row{{0}},
+	},
+	{
+		Query:    "SELECT TIMESTAMPDIFF(YEAR, DATE '2025-07-04', DATE '2026-07-03')",
+		Expected: []sql.Row{{0}},
+	},
+	{
+		Query:    "SELECT TIMESTAMPDIFF(YEAR, DATE '2026-07-03', DATE '2025-07-04')",
+		Expected: []sql.Row{{0}},
+	},
 	// TRIM Function Tests
 	{
 		Query:    `SELECT TRIM(mytable.s) AS s FROM mytable`,

sql/expression/function/time_math.go

@@ -689,6 +689,7 @@ func (t *TimestampDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error)
 	case "week":
 		res = int64(diff.Hours() / (24 * 7))
 	case "month":
+		// TODO: this calculation is not correct. Not every month is 30 days https://github.com/dolthub/dolt/issues/10393
 		res = int64(diff.Hours() / (24 * 30))
 		if res > 0 {
 			if date2.Day()-date1.Day() < 0 {
@@ -702,6 +703,7 @@ func (t *TimestampDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error)
 			}
 		}
 	case "quarter":
+		// TODO: this calculation is not correct. Not every month is 30 days https://github.com/dolthub/dolt/issues/10393
 		monthRes := int64(diff.Hours() / (24 * 30))
 		if monthRes > 0 {
 			if date2.Day()-date1.Day() < 0 {
@@ -716,25 +718,42 @@ func (t *TimestampDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error)
 		}
 		res = monthRes / 3
 	case "year":
-		yearRes := int64(diff.Hours() / (24 * 365))
-		if yearRes > 0 {
-			monthRes := int64(diff.Hours() / (24 * 30))
-			if monthRes > 0 {
-				if date2.Day()-date1.Day() < 0 {
-					monthRes -= 1
-				} else if date2.Hour()-date1.Hour() < 0 {
-					monthRes -= 1
-				} else if date2.Minute()-date1.Minute() < 0 {
-					monthRes -= 1
-				} else if date2.Second()-date1.Second() < 0 {
-					monthRes -= 1
+		if diff == 0 {
+			return 0, nil
+		}
+		negate := false
+		before := date1
+		after := date2
+		if diff < 0 {
+			negate = true
+			before = date2
+			after = date1
+		}
+
+		beforeYear, beforeMonth, beforeDay := before.Date()
+		afterYear, afterMonth, afterDay := after.Date()
+		yearDiff := afterYear - beforeYear
+		if beforeMonth > afterMonth {
+			yearDiff -= 1
+		} else if beforeMonth == afterMonth {
+			if beforeDay > afterDay {
+				yearDiff -= 1
+			} else if beforeDay == afterDay {
+				beforeHour, beforeMin, beforeSec := before.Clock()
+				afterHour, afterMin, afterSec := after.Clock()
+				secondDiff := (afterHour-beforeHour)*3600 + (afterMin-beforeMin)*60 + (afterSec - beforeSec)
+				if secondDiff < 0 {
+					yearDiff -= 1
+				} else if secondDiff == 0 && before.Nanosecond() > after.Nanosecond() {
+					yearDiff -= 1
 				}
 			}
-			res = monthRes / 12
-		} else {
-			res = yearRes
 		}
 
+		res = int64(yearDiff)
+		if negate {
+			res = -res
+		}
 	default:
 		return nil, errors.NewKind("invalid interval unit: %s").New(unit)
 	}

sql/expression/function/time_math_test.go

@@ -652,9 +652,10 @@ func TestTimestampDiff(t *testing.T) {
 		{"quarter - second less than a quarter", types.Text, types.Text, types.Text, sql.NewRow("SQL_TSI_QUARTER", "2007-08-30 00:00:01", "2007-11-30 00:00:00"), int64(0), false},
 		{"quarter", types.Text, types.Text, types.Text, sql.NewRow("QUARTER", "2006-08-30 00:00:00", "2007-11-30 00:00:00"), int64(5), false},
 		{"quarter - negative", types.Text, types.Text, types.Text, sql.NewRow("QUARTER", "2006-08-30 00:00:00", "2002-11-30 00:00:00"), int64(-15), false},
-		{"year - second less than a month", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2019-01-01 00:00:00", "2019-12-31 23:59:59"), int64(0), false},
-		{"year", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2016-09-04 00:00:01", "2021-09-04 00:00:00"), int64(4), false},
-		{"year - ", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2016-09-04 01:00:01", "2021-09-04 02:00:02"), int64(5), false},
+		{"year - same year", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2019-01-01 00:00:00", "2019-12-31 23:59:59"), int64(0), false},
+		{"year - one second less than five years", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2016-09-04 00:00:01", "2021-09-04 00:00:00"), int64(4), false},
+		{"year - one hour more than five years", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2016-09-04 01:00:01", "2021-09-04 02:00:02"), int64(5), false},
+		{"year - one microsecond less than five years", types.Text, types.Text, types.Text, sql.NewRow("YEAR", "2016-09-04 01:00:02.000001", "2021-09-04 01:00:02"), int64(4), false},
 		{"year - negative", types.Text, types.Text, types.Text, sql.NewRow("SQL_TSI_YEAR", "2016-09-05 00:00:00", "2006-09-04 23:59:59"), int64(-10), false},
 		{"unit is null", types.Text, types.Text, types.Text, sql.NewRow(nil, "2016-09-05 00:00:00", "2006-09-04 23:59:59"), nil, true},
 		{"first timestamp is null", types.Text, types.Text, types.Text, sql.NewRow("YEAR", nil, "2021-09-04 02:00:02"), nil, false},