1 files changed, 195 insertions, 0 deletions
diff --git a/weed/query/engine/datetime_functions.go b/weed/query/engine/datetime_functions.go
new file mode 100644
index 000000000..2ece58e15
--- /dev/null
+++ b/weed/query/engine/datetime_functions.go
@@ -0,0 +1,195 @@
+package engine
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/schema_pb"
+)
+
+// ===============================
+// DATE/TIME CONSTANTS
+// ===============================
+
+// CurrentDate returns the current date as a string in YYYY-MM-DD format
+func (e *SQLEngine) CurrentDate() (*schema_pb.Value, error) {
+	now := time.Now()
+	dateStr := now.Format("2006-01-02")
+	
+	return &schema_pb.Value{
+		Kind: &schema_pb.Value_StringValue{StringValue: dateStr},
+	}, nil
+}
+
+// CurrentTimestamp returns the current timestamp
+func (e *SQLEngine) CurrentTimestamp() (*schema_pb.Value, error) {
+	now := time.Now()
+	
+	// Return as TimestampValue with microseconds
+	timestampMicros := now.UnixMicro()
+	
+	return &schema_pb.Value{
+		Kind: &schema_pb.Value_TimestampValue{
+			TimestampValue: &schema_pb.TimestampValue{
+				TimestampMicros: timestampMicros,
+			},
+		},
+	}, nil
+}
+
+// CurrentTime returns the current time as a string in HH:MM:SS format
+func (e *SQLEngine) CurrentTime() (*schema_pb.Value, error) {
+	now := time.Now()
+	timeStr := now.Format("15:04:05")
+	
+	return &schema_pb.Value{
+		Kind: &schema_pb.Value_StringValue{StringValue: timeStr},
+	}, nil
+}
+
+// Now is an alias for CurrentTimestamp (common SQL function name)
+func (e *SQLEngine) Now() (*schema_pb.Value, error) {
+	return e.CurrentTimestamp()
+}
+
+// ===============================
+// EXTRACT FUNCTION
+// ===============================
+
+// DatePart represents the part of a date/time to extract
+type DatePart string
+
+const (
+	PartYear     DatePart = "YEAR"
+	PartMonth    DatePart = "MONTH"
+	PartDay      DatePart = "DAY"
+	PartHour     DatePart = "HOUR"
+	PartMinute   DatePart = "MINUTE"
+	PartSecond   DatePart = "SECOND"
+	PartWeek     DatePart = "WEEK"
+	PartDayOfYear DatePart = "DOY"
+	PartDayOfWeek DatePart = "DOW"
+	PartQuarter   DatePart = "QUARTER"
+	PartEpoch     DatePart = "EPOCH"
+)
+
+// Extract extracts a specific part from a date/time value
+func (e *SQLEngine) Extract(part DatePart, value *schema_pb.Value) (*schema_pb.Value, error) {
+	if value == nil {
+		return nil, fmt.Errorf("EXTRACT function requires non-null value")
+	}
+
+	// Convert value to time
+	t, err := e.valueToTime(value)
+	if err != nil {
+		return nil, fmt.Errorf("EXTRACT function time conversion error: %v", err)
+	}
+
+	var result int64
+
+	switch strings.ToUpper(string(part)) {
+	case string(PartYear):
+		result = int64(t.Year())
+	case string(PartMonth):
+		result = int64(t.Month())
+	case string(PartDay):
+		result = int64(t.Day())
+	case string(PartHour):
+		result = int64(t.Hour())
+	case string(PartMinute):
+		result = int64(t.Minute())
+	case string(PartSecond):
+		result = int64(t.Second())
+	case string(PartWeek):
+		_, week := t.ISOWeek()
+		result = int64(week)
+	case string(PartDayOfYear):
+		result = int64(t.YearDay())
+	case string(PartDayOfWeek):
+		result = int64(t.Weekday())
+	case string(PartQuarter):
+		month := t.Month()
+		result = int64((month-1)/3 + 1)
+	case string(PartEpoch):
+		result = t.Unix()
+	default:
+		return nil, fmt.Errorf("unsupported date part: %s", part)
+	}
+
+	return &schema_pb.Value{
+		Kind: &schema_pb.Value_Int64Value{Int64Value: result},
+	}, nil
+}
+
+// ===============================
+// DATE_TRUNC FUNCTION
+// ===============================
+
+// DateTrunc truncates a date/time to the specified precision
+func (e *SQLEngine) DateTrunc(precision string, value *schema_pb.Value) (*schema_pb.Value, error) {
+	if value == nil {
+		return nil, fmt.Errorf("DATE_TRUNC function requires non-null value")
+	}
+
+	// Convert value to time
+	t, err := e.valueToTime(value)
+	if err != nil {
+		return nil, fmt.Errorf("DATE_TRUNC function time conversion error: %v", err)
+	}
+
+	var truncated time.Time
+
+	switch strings.ToLower(precision) {
+	case "microsecond", "microseconds":
+		// No truncation needed for microsecond precision
+		truncated = t
+	case "millisecond", "milliseconds":
+		truncated = t.Truncate(time.Millisecond)
+	case "second", "seconds":
+		truncated = t.Truncate(time.Second)
+	case "minute", "minutes":
+		truncated = t.Truncate(time.Minute)
+	case "hour", "hours":
+		truncated = t.Truncate(time.Hour)
+	case "day", "days":
+		truncated = time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
+	case "week", "weeks":
+		// Truncate to beginning of week (Monday)
+		days := int(t.Weekday())
+		if days == 0 { // Sunday = 0, adjust to make Monday = 0
+			days = 6
+		} else {
+			days = days - 1
+		}
+		truncated = time.Date(t.Year(), t.Month(), t.Day()-days, 0, 0, 0, 0, t.Location())
+	case "month", "months":
+		truncated = time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, t.Location())
+	case "quarter", "quarters":
+		month := t.Month()
+		quarterMonth := ((int(month)-1)/3)*3 + 1
+		truncated = time.Date(t.Year(), time.Month(quarterMonth), 1, 0, 0, 0, 0, t.Location())
+	case "year", "years":
+		truncated = time.Date(t.Year(), 1, 1, 0, 0, 0, 0, t.Location())
+	case "decade", "decades":
+		year := (t.Year()/10) * 10
+		truncated = time.Date(year, 1, 1, 0, 0, 0, 0, t.Location())
+	case "century", "centuries":
+		year := ((t.Year()-1)/100)*100 + 1
+		truncated = time.Date(year, 1, 1, 0, 0, 0, 0, t.Location())
+	case "millennium", "millennia":
+		year := ((t.Year()-1)/1000)*1000 + 1
+		truncated = time.Date(year, 1, 1, 0, 0, 0, 0, t.Location())
+	default:
+		return nil, fmt.Errorf("unsupported date truncation precision: %s", precision)
+	}
+
+	// Return as TimestampValue
+	return &schema_pb.Value{
+		Kind: &schema_pb.Value_TimestampValue{
+			TimestampValue: &schema_pb.TimestampValue{
+				TimestampMicros: truncated.UnixMicro(),
+			},
+		},
+	}, nil
+}