diff --git a/sql3/errors.go b/sql3/errors.go
index 620abcf47..44cd761c8 100644
--- a/sql3/errors.go
+++ b/sql3/errors.go
@@ -138,10 +138,9 @@ const (
 	// time quantum function eval
 	ErrQRangeFromAndToTimeCannotBeBothNull errors.Code = "ErrQRangeFromAndToTimeCannotBeBothNull"
 	ErrQRangeInvalidUse                    errors.Code = "ErrQRangeInvalidUse"
-	ErrYearOutOfRange                      errors.Code = "ErrYearOutOfRange"
-
-	//evaluate errors
-	ErrDivideByZero errors.Code = "ErrDivideByZero"
+	ErrInvalidDatetimePart                 errors.Code = "ErrInvalidDatetimePart"
+	ErrOutputValueOutOfRange               errors.Code = "ErrOutputValueOutOfRange"
+	ErrDivideByZero                        errors.Code = "ErrDivideByZero"
 )
 
 func NewErrDuplicateColumn(line int, col int, column string) error {
@@ -857,10 +856,17 @@ func NewErrQRangeInvalidUse(line, col int) error {
 	)
 }
 
-func NewErrYearOutOfRange(line, col int, year int) error {
+func NewErrInvalidDatetimePart(line, col int, datetimepart int) error {
 	return errors.New(
-		ErrYearOutOfRange,
-		fmt.Sprintf("[%d:%d] year '%d' out of range [0,9999]", line, col, year),
+		ErrInvalidDatetimePart,
+		fmt.Sprintf("[%d:%d] not a valid datetimepart %d", line, col, datetimepart),
+	)
+}
+
+func NewErrOutputValueOutOfRange(line, col int) error {
+	return errors.New(
+		ErrOutputValueOutOfRange,
+		fmt.Sprintf("[%d:%d] output value out of range", line, col),
 	)
 }
 
diff --git a/sql3/planner/expression.go b/sql3/planner/expression.go
index 6518575ec..058b92a14 100644
--- a/sql3/planner/expression.go
+++ b/sql3/planner/expression.go
@@ -1588,6 +1588,8 @@ func (n *callPlanExpression) Evaluate(currentRow []interface{}) (interface{}, er
 		return n.EvaluateDateTimeFromParts(currentRow)
 	case "DATETIMEADD":
 		return n.EvaluateDatetimeAdd(currentRow)
+	case "DATETIMEDIFF":
+		return n.EvaluateDatetimeDiff(currentRow)
 	default:
 		return nil, sql3.NewErrInternalf("unhandled function name '%s'", n.name)
 	}
diff --git a/sql3/planner/expressionanalyzercall.go b/sql3/planner/expressionanalyzercall.go
index 2b6745d1b..dac0451d7 100644
--- a/sql3/planner/expressionanalyzercall.go
+++ b/sql3/planner/expressionanalyzercall.go
@@ -263,9 +263,10 @@ func (p *ExecutionPlanner) analyzeCallExpression(ctx context.Context, call *pars
 		return p.analyzeFunctionRangeQ(call, scope)
 	case "DATETIMEFROMPARTS":
 		return p.analyzeFunctionDateTimeFromParts(call, scope)
-
 	case "DATETIMEADD":
 		return p.analyzeFunctionDatetimeAdd(call, scope)
+	case "DATETIMEDIFF":
+		return p.analyzeFunctionDateTimeDiff(call, scope)
 	default:
 		return nil, sql3.NewErrCallUnknownFunction(call.Name.NamePos.Line, call.Name.NamePos.Column, call.Name.Name)
 	}
diff --git a/sql3/planner/inbuiltfunctionsdate.go b/sql3/planner/inbuiltfunctionsdate.go
index 1bdc69c88..6e2a8d7ea 100644
--- a/sql3/planner/inbuiltfunctionsdate.go
+++ b/sql3/planner/inbuiltfunctionsdate.go
@@ -144,6 +144,31 @@ func (p *ExecutionPlanner) analyzeFunctionDateTimeName(call *parser.Call, scope
 	return call, nil
 }
 
+// analyzeFunctionDateTimeDiff ensures a timeunit and start and end timestamps.
+func (p *ExecutionPlanner) analyzeFunctionDateTimeDiff(call *parser.Call, scope parser.Statement) (parser.Expr, error) {
+	if len(call.Args) != 3 {
+		return nil, sql3.NewErrCallParameterCountMismatch(call.Rparen.Line, call.Rparen.Column, call.Name.Name, 3, len(call.Args))
+	}
+
+	// interval
+	intervalType := parser.NewDataTypeString()
+	if !typesAreAssignmentCompatible(intervalType, call.Args[0].DataType()) {
+		return nil, sql3.NewErrParameterTypeMistmatch(call.Args[0].Pos().Line, call.Args[0].Pos().Column, call.Args[0].DataType().TypeDescription(), intervalType.TypeDescription())
+	}
+
+	dateType := parser.NewDataTypeTimestamp()
+	if !typesAreAssignmentCompatible(dateType, call.Args[1].DataType()) {
+		return nil, sql3.NewErrParameterTypeMistmatch(call.Args[1].Pos().Line, call.Args[1].Pos().Column, call.Args[1].DataType().TypeDescription(), dateType.TypeDescription())
+	}
+
+	if !typesAreAssignmentCompatible(dateType, call.Args[2].DataType()) {
+		return nil, sql3.NewErrParameterTypeMistmatch(call.Args[2].Pos().Line, call.Args[2].Pos().Column, call.Args[2].DataType().TypeDescription(), dateType.TypeDescription())
+	}
+
+	call.ResultDataType = parser.NewDataTypeInt()
+	return call, nil
+}
+
 func (n *callPlanExpression) EvaluateDateTimePart(currentRow []interface{}) (interface{}, error) {
 	intervalEval, err := n.args[0].Evaluate(currentRow)
 	if err != nil {
@@ -247,13 +272,61 @@ func (n *callPlanExpression) EvaluateDateTimeFromParts(currentRow []interface{})
 		timestamps[i] = int(val)
 	}
 
+	if val, ok := isValidDateTimeParts(timestamps); !ok {
+		return nil, sql3.NewErrInvalidDatetimePart(0, 0, val)
+	}
+
 	dt := time.Date(timestamps[0], time.Month(timestamps[1]), timestamps[2], timestamps[3], timestamps[4], timestamps[5], timestamps[6]*1000*1000, time.UTC)
 	if dt.Year() < 0 || dt.Year() > 9999 {
-		return nil, sql3.NewErrYearOutOfRange(0, 0, dt.Year())
+		return nil, sql3.NewErrInvalidDatetimePart(0, 0, dt.Year())
 	}
 	return dt, nil
 }
 
+// isValidDateTimeParts returns true if the year is between 0 and 9999 and the date and time exists(think of leap year).
+// the argument is a slice of ints representing the year, month, day, hour, minutes, seconds, and milliseconds.
+// If any value in the slice falls outside its range, the value and false are returned.
+func isValidDateTimeParts(timestamps []int) (value int, ok bool) {
+	if timestamps[0] < 0 || timestamps[0] > 9999 {
+		return timestamps[0], false
+	}
+	if timestamps[1] < 1 || timestamps[1] > 12 {
+		return timestamps[1], false
+	}
+	switch timestamps[1] {
+	case 1, 3, 5, 7, 8, 10, 12:
+		if timestamps[2] < 1 || timestamps[2] > 31 {
+			return timestamps[2], false
+		}
+	case 4, 6, 9, 11:
+		if timestamps[2] < 1 || timestamps[2] > 30 {
+			return timestamps[2], false
+		}
+	case 2:
+		if timestamps[2] < 1 || timestamps[2] > 29 {
+			return timestamps[2], false
+		}
+		if !(timestamps[0]%4 == 0 && timestamps[0]%100 != 0 || timestamps[0]%400 == 0) {
+			if timestamps[2] == 29 {
+				return timestamps[2], false
+			}
+		}
+	}
+	if timestamps[3] < 0 || timestamps[3] > 23 {
+		return timestamps[3], false
+	}
+	if timestamps[4] < 0 || timestamps[4] > 59 {
+		return timestamps[4], false
+	}
+	if timestamps[5] < 0 || timestamps[5] > 59 {
+		return timestamps[5], false
+	}
+	if timestamps[6] < 0 || timestamps[6] > 999 {
+		return timestamps[6], false
+	}
+	return 0, true
+}
+
 func (n *callPlanExpression) EvaluateToTimestamp(currentRow []interface{}) (interface{}, error) {
 	// retrieve param1, the number to be converted to timestamp
 	param1, err := n.args[0].Evaluate(currentRow)
@@ -478,3 +551,87 @@ func isValidTimeInterval(unit string) bool {
 		return false
 	}
 }
+
+// EvaluateDatetimeDiff takes three arguments:
+// 1. param1, timeunit of the value to be subtracted from the target timestamp
+// 2. param2, starttime to be subtracted from the endtime timestamp
+// 3. param3, endtime timestamp to which the starttime to be subtracted from.
+// It returns the difference between the two timestamps.
+func (n *callPlanExpression) EvaluateDatetimeDiff(currentRow []interface{}) (interface{}, error) {
+	param1, err := n.args[0].Evaluate(currentRow)
+	if err != nil {
+		return nil, err
+	}
+	if param1 == nil {
+		return nil, nil
+	}
+	cp, err := coerceValue(n.args[0].Type(), parser.NewDataTypeString(), param1, parser.Pos{Line: 0, Column: 0})
+	if err != nil {
+		return nil, err
+	}
+	timeunit, ok := cp.(string)
+	if !ok {
+		return nil, sql3.NewErrInternalf("unable to convert value")
+	}
+
+	param2, err := n.args[1].Evaluate(currentRow)
+	if err != nil {
+		return nil, err
+	}
+	coercedParam, err := coerceValue(n.args[1].Type(), parser.NewDataTypeTimestamp(), param2, parser.Pos{Line: 0, Column: 0})
+	if err != nil {
+		return nil, err
+	}
+	if coercedParam == nil {
+		return nil, nil
+	}
+	startDate, ok := coercedParam.(time.Time)
+	if !ok {
+		return nil, sql3.NewErrInternalf("unable to convert value")
+	}
+	if coercedParam == nil {
+		return nil, nil
+	}
+	param3, err := n.args[2].Evaluate(currentRow)
+	if err != nil {
+		return nil, err
+	}
+	if param3 == nil {
+		return nil, nil
+	}
+	coercedParam, err = coerceValue(n.args[2].Type(), parser.NewDataTypeTimestamp(), param3, parser.Pos{Line: 0, Column: 0})
+	if err != nil {
+		return nil, err
+	}
+	endDate, ok := coercedParam.(time.Time)
+	if !ok {
+		return nil, sql3.NewErrInternalf("unable to convert value")
+	}
+	var diff int64
+	switch strings.ToUpper(timeunit) {
+	case intervalYear:
+		diff = int64(endDate.Year() - startDate.Year())
+	case intervalMonth:
+		diff = int64((endDate.Year()-startDate.Year())*12 + int(endDate.Month()-startDate.Month()))
+	case intervalDay:
+		diff = int64(endDate.Sub(startDate).Hours() / 24)
+	case intervalHour:
+		diff = int64(endDate.Sub(startDate).Hours())
+	case intervalMinute:
+		diff = int64(endDate.Sub(startDate).Minutes())
+	case intervalSecond:
+		diff = int64(endDate.Sub(startDate).Seconds())
+	case intervalMillisecond:
+		diff = endDate.Sub(startDate).Milliseconds()
+	case intervalMicrosecond:
+		diff = endDate.Sub(startDate).Microseconds()
+	case intervalNanosecond:
+		diff = endDate.Sub(startDate).Nanoseconds()
+	default:
+		return nil, sql3.NewErrCallParameterValueInvalid(0, 0, timeunit, "timeunit")
+	}
+	if diff == (-1<<63) || diff == ((1<<63)-1) {
+		return nil, sql3.NewErrOutputValueOutOfRange(0, 0)
+	}
+	return diff, nil
+}
diff --git a/sql3/test/defs/defs.go b/sql3/test/defs/defs.go
index 75c88dd70..3cc449b47 100644
--- a/sql3/test/defs/defs.go
+++ b/sql3/test/defs/defs.go
@@ -49,6 +49,7 @@ var TableTests []TableTest = []TableTest{
 	dateTimeNameTests,
 	toTimestampTests,
 	datetimeAddTests,
+	datetimedifftests,
 
 	stringScalarFunctionsTests,
 
@@ -224,6 +225,19 @@ func knownSubSecondTimestamp() time.Time {
 	return tm
 }
 
+func knownSubSecondTimestamp2() time.Time {
+	tm, err := time.ParseInLocation(time.RFC3339, "2022-12-09T18:04:54+00:00", time.UTC)
+	if err != nil {
+		panic(err.Error())
+	}
+	duration, err := time.ParseDuration("300500800ns")
+	if err != nil {
+		panic(err.Error())
+	}
+	tm = tm.Add(duration)
+	return tm
+}
+
 func timestampFromString(s string) time.Time {
 	tm, err := time.ParseInLocation(time.RFC3339, s, time.UTC)
 	if err != nil {
diff --git a/sql3/test/defs/defs_date_functions.go b/sql3/test/defs/defs_date_functions.go
index 3db762ecc..94e2c9b6b 100644
--- a/sql3/test/defs/defs_date_functions.go
+++ b/sql3/test/defs/defs_date_functions.go
@@ -328,11 +328,18 @@ var toTimestampTests = TableTest{
 			ExpErr: "an expression of type 'string' cannot be passed to a parameter of type 'int'",
 		},
 		{
-			name: "DateTimeFromPartsYearOutOfRange",
+			name: "DateTimeFromPartsInvalidDatetimePart",
 			SQLs: sqls(
 				"select datetimefromparts(10000,1,1,1,1,1,1)",
 			),
-			ExpErr: "[0:0] year '10000' out of range [0,9999]",
+			ExpErr: "[0:0] not a valid datetimepart 10000",
+		},
+		{
+			name: "DateTimeFromPartsInvalidDatetimePart2",
+			SQLs: sqls(
+				"select datetimefromparts(2023,2,29,1,1,1,1)",
+			),
+			ExpErr: "[0:0] not a valid datetimepart 29",
 		},
 		{
 			name: "DateTimeFromPartsKnownTimestamp",
@@ -651,3 +658,162 @@ var datetimeAddTests = TableTest{
 		},
 	},
 }
+
+var datetimedifftests = TableTest{
+	name: "DatetimeDiff",
+	Table: tbl("dttable",
+		srcHdrs(
+			srcHdr("_id", fldTypeID),
+			srcHdr("startTime", fldTypeTimestamp, "timeunit 'ns'"),
+			srcHdr("endTime", fldTypeTimestamp, "timeunit 'ns'"),
+		),
+		srcRows(
+			srcRow(int64(1), knownSubSecondTimestamp(), knownSubSecondTimestamp2()),
+		)),
+	SQLTests: []SQLTest{
+		{
+			name: "DatetimeDiffWrongParamCount",
+			SQLs: sqls(
+				"select datetimediff(startTime, endTime) from dttable;",
+			),
+			ExpErr: "count of formal parameters (3) does not match count of actual parameters (2)",
+		},
+		{
+			name: "DatetimeDiffInvalidType",
+			SQLs: sqls(
+				"select datetimediff('yy','nope', endTime) from dttable;",
+			),
+			ExpErr: "[0:0] unable to convert 'nope' to type 'timestamp'",
+		},
+		{
+			name: "DatetimeDiffNull",
+			SQLs: sqls(
+				"select datetimediff(null, startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(nil),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffYY",
+			SQLs: sqls(
+				"select datetimediff('yy', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(10)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffM",
+			SQLs: sqls(
+				"select datetimediff('m', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(121)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffD",
+			SQLs: sqls(
+				"select datetimediff('d', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(3689)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffHH",
+			SQLs: sqls(
+				"select datetimediff('hh', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(88555)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffMI",
+			SQLs: sqls(
+				"select datetimediff('mi', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(5313356)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffS",
+			SQLs: sqls(
+				"select datetimediff('s', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(318801373)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffMS",
+			SQLs: sqls(
+				"select datetimediff('ms', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(318801373200)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffUS",
+			SQLs: sqls(
+				"select datetimediff('us', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(318801373200300)),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			name: "DatetimeDiffNS",
+			SQLs: sqls(
+				"select datetimediff('ns', startTime, endTime) from dttable;",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeInt),
+			),
+			ExpRows: rows(
+				row(int64(318801373200300500)),
+			),
+			Compare: CompareExactUnordered,
+		},
+	},
+}