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date.go
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date.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package function
import (
"fmt"
"strings"
"time"
"github.com/dolthub/go-mysql-server/sql"
"github.com/dolthub/go-mysql-server/sql/expression"
)
// DateAdd adds an interval to a date.
type DateAdd struct {
Date sql.Expression
Interval *expression.Interval
}
var _ sql.FunctionExpression = (*DateAdd)(nil)
// NewDateAdd creates a new date add function.
func NewDateAdd(args ...sql.Expression) (sql.Expression, error) {
if len(args) != 2 {
return nil, sql.ErrInvalidArgumentNumber.New("DATE_ADD", 2, len(args))
}
i, ok := args[1].(*expression.Interval)
if !ok {
return nil, fmt.Errorf("DATE_ADD expects an interval as second parameter")
}
return &DateAdd{args[0], i}, nil
}
// FunctionName implements sql.FunctionExpression
func (d *DateAdd) FunctionName() string {
return "date_add"
}
// Description implements sql.FunctionExpression
func (d *DateAdd) Description() string {
return "adds the interval to the given date."
}
// Children implements the sql.Expression interface.
func (d *DateAdd) Children() []sql.Expression {
return []sql.Expression{d.Date, d.Interval}
}
// Resolved implements the sql.Expression interface.
func (d *DateAdd) Resolved() bool {
return d.Date.Resolved() && d.Interval.Resolved()
}
// IsNullable implements the sql.Expression interface.
func (d *DateAdd) IsNullable() bool {
return true
}
// Type implements the sql.Expression interface.
func (d *DateAdd) Type() sql.Type {
sqlType := dateOffsetType(d.Date, d.Interval)
return sqlType
}
// WithChildren implements the Expression interface.
func (d *DateAdd) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewDateAdd(children...)
}
// Eval implements the sql.Expression interface.
func (d *DateAdd) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
date, err := d.Date.Eval(ctx, row)
if err != nil {
return nil, err
}
if date == nil {
return nil, nil
}
date, err = sql.Datetime.Convert(date)
if err != nil {
return nil, err
}
delta, err := d.Interval.EvalDelta(ctx, row)
if err != nil {
return nil, err
}
if delta == nil {
return nil, nil
}
return sql.ValidateTime(delta.Add(date.(time.Time))), nil
}
func (d *DateAdd) String() string {
return fmt.Sprintf("DATE_ADD(%s, %s)", d.Date, d.Interval)
}
// DateSub subtracts an interval from a date.
type DateSub struct {
Date sql.Expression
Interval *expression.Interval
}
var _ sql.FunctionExpression = (*DateSub)(nil)
// NewDateSub creates a new date add function.
func NewDateSub(args ...sql.Expression) (sql.Expression, error) {
if len(args) != 2 {
return nil, sql.ErrInvalidArgumentNumber.New("DATE_SUB", 2, len(args))
}
i, ok := args[1].(*expression.Interval)
if !ok {
return nil, fmt.Errorf("DATE_SUB expects an interval as second parameter")
}
return &DateSub{args[0], i}, nil
}
// FunctionName implements sql.FunctionExpression
func (d *DateSub) FunctionName() string {
return "date_sub"
}
// Description implements sql.FunctionExpression
func (d *DateSub) Description() string {
return "subtracts the interval from the given date."
}
// Children implements the sql.Expression interface.
func (d *DateSub) Children() []sql.Expression {
return []sql.Expression{d.Date, d.Interval}
}
// Resolved implements the sql.Expression interface.
func (d *DateSub) Resolved() bool {
return d.Date.Resolved() && d.Interval.Resolved()
}
// IsNullable implements the sql.Expression interface.
func (d *DateSub) IsNullable() bool {
return true
}
// Type implements the sql.Expression interface.
func (d *DateSub) Type() sql.Type {
sqlType := dateOffsetType(d.Date, d.Interval)
return sqlType
}
// WithChildren implements the Expression interface.
func (d *DateSub) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewDateSub(children...)
}
// Eval implements the sql.Expression interface.
func (d *DateSub) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
date, err := d.Date.Eval(ctx, row)
if err != nil {
return nil, err
}
if date == nil {
return nil, nil
}
date, err = sql.Datetime.Convert(date)
if err != nil {
return nil, err
}
delta, err := d.Interval.EvalDelta(ctx, row)
if err != nil {
return nil, err
}
if delta == nil {
return nil, nil
}
return sql.ValidateTime(delta.Sub(date.(time.Time))), nil
}
func (d *DateSub) String() string {
return fmt.Sprintf("DATE_SUB(%s, %s)", d.Date, d.Interval)
}
// TimestampConversion is a shorthand function for CONVERT(expr, TIMESTAMP)
type TimestampConversion struct {
Date sql.Expression
}
var _ sql.FunctionExpression = (*TimestampConversion)(nil)
// FunctionName implements sql.FunctionExpression
func (t *TimestampConversion) FunctionName() string {
return "timestamp"
}
// Description implements sql.FunctionExpression
func (t *TimestampConversion) Description() string {
return "returns a timestamp value for the expression given (e.g. the string '2020-01-02')."
}
func (t *TimestampConversion) Resolved() bool {
return t.Date == nil || t.Date.Resolved()
}
func (t *TimestampConversion) String() string {
return fmt.Sprintf("TIMESTAMP(%s)", t.Date)
}
func (t *TimestampConversion) Type() sql.Type {
return sql.Timestamp
}
func (t *TimestampConversion) IsNullable() bool {
return false
}
func (t *TimestampConversion) Eval(ctx *sql.Context, r sql.Row) (interface{}, error) {
e, err := t.Date.Eval(ctx, r)
if err != nil {
return nil, err
}
return sql.Timestamp.Convert(e)
}
func (t *TimestampConversion) Children() []sql.Expression {
if t.Date == nil {
return nil
}
return []sql.Expression{t.Date}
}
func (t *TimestampConversion) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewTimestamp(children...)
}
func NewTimestamp(args ...sql.Expression) (sql.Expression, error) {
if len(args) != 1 {
return nil, sql.ErrInvalidArgumentNumber.New("TIMESTAMP", 1, len(args))
}
return &TimestampConversion{args[0]}, nil
}
// DatetimeConversion is a shorthand function for CONVERT(expr, DATETIME)
type DatetimeConversion struct {
Date sql.Expression
}
var _ sql.FunctionExpression = (*DatetimeConversion)(nil)
// FunctionName implements sql.FunctionExpression
func (t *DatetimeConversion) FunctionName() string {
return "datetime"
}
// Description implements sql.FunctionExpression
func (t *DatetimeConversion) Description() string {
return "returns a DATETIME value for the expression given (e.g. the string '2020-01-02')."
}
func (t *DatetimeConversion) Resolved() bool {
return t.Date == nil || t.Date.Resolved()
}
func (t *DatetimeConversion) String() string {
return fmt.Sprintf("DATETIME(%s)", t.Date)
}
func (t *DatetimeConversion) Type() sql.Type {
return sql.Datetime
}
func (t *DatetimeConversion) IsNullable() bool {
return false
}
func (t *DatetimeConversion) Eval(ctx *sql.Context, r sql.Row) (interface{}, error) {
e, err := t.Date.Eval(ctx, r)
if err != nil {
return nil, err
}
return sql.Datetime.Convert(e)
}
func (t *DatetimeConversion) Children() []sql.Expression {
if t.Date == nil {
return nil
}
return []sql.Expression{t.Date}
}
func (t *DatetimeConversion) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewDatetime(children...)
}
// NewDatetime returns a DatetimeConversion instance to handle the sql function "datetime". This is
// not a standard mysql function, but provides a shorthand for datetime conversions.
func NewDatetime(args ...sql.Expression) (sql.Expression, error) {
if len(args) != 1 {
return nil, sql.ErrInvalidArgumentNumber.New("DATETIME", 1, len(args))
}
return &DatetimeConversion{args[0]}, nil
}
// UnixTimestamp converts the argument to the number of seconds since 1970-01-01 00:00:00 UTC.
// With no argument, returns number of seconds since unix epoch for the current time.
type UnixTimestamp struct {
Date sql.Expression
}
var _ sql.FunctionExpression = (*UnixTimestamp)(nil)
func NewUnixTimestamp(args ...sql.Expression) (sql.Expression, error) {
if len(args) > 1 {
return nil, sql.ErrInvalidArgumentNumber.New("UNIX_TIMESTAMP", 1, len(args))
}
if len(args) == 0 {
return &UnixTimestamp{nil}, nil
}
return &UnixTimestamp{args[0]}, nil
}
// FunctionName implements sql.FunctionExpression
func (ut *UnixTimestamp) FunctionName() string {
return "unix_timestamp"
}
// Description implements sql.FunctionExpression
func (ut *UnixTimestamp) Description() string {
return "returns the datetime argument to the number of seconds since the Unix epoch. With no argument, returns the number of seconds since the Unix epoch for the current time."
}
func (ut *UnixTimestamp) Children() []sql.Expression {
if ut.Date != nil {
return []sql.Expression{ut.Date}
}
return nil
}
func (ut *UnixTimestamp) Resolved() bool {
if ut.Date != nil {
return ut.Date.Resolved()
}
return true
}
func (ut *UnixTimestamp) IsNullable() bool {
return true
}
func (ut *UnixTimestamp) Type() sql.Type {
return sql.Float64
}
func (ut *UnixTimestamp) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NewUnixTimestamp(children...)
}
func (ut *UnixTimestamp) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
if ut.Date == nil {
return toUnixTimestamp(ctx.QueryTime())
}
date, err := ut.Date.Eval(ctx, row)
if err != nil {
return nil, err
}
if date == nil {
return nil, nil
}
date, err = sql.Datetime.Convert(date)
if err != nil {
// If we aren't able to convert the value to a date, return 0 and set
// a warning to match MySQL's behavior
ctx.Warn(1292, "Incorrect datetime value: %s", ut.Date.String())
return 0, nil
}
return toUnixTimestamp(date.(time.Time))
}
func toUnixTimestamp(t time.Time) (interface{}, error) {
return sql.Float64.Convert(float64(t.Unix()) + float64(t.Nanosecond())/float64(1000000000))
}
func (ut *UnixTimestamp) String() string {
if ut.Date != nil {
return fmt.Sprintf("UNIX_TIMESTAMP(%s)", ut.Date)
} else {
return "UNIX_TIMESTAMP()"
}
}
// FromUnixtime converts the argument to a datetime.
type FromUnixtime struct {
*UnaryFunc
}
var _ sql.FunctionExpression = (*FromUnixtime)(nil)
func NewFromUnixtime(arg sql.Expression) sql.Expression {
return &FromUnixtime{NewUnaryFunc(arg, "FROM_UNIXTIME", sql.Datetime)}
}
// Description implements sql.FunctionExpression
func (r *FromUnixtime) Description() string {
return "formats Unix timestamp as a date."
}
func (r *FromUnixtime) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
val, err := r.EvalChild(ctx, row)
if err != nil {
return nil, err
}
if val == nil {
return nil, nil
}
n, err := sql.Int64.Convert(val)
if err != nil {
return nil, err
}
return time.Unix(n.(int64), 0), nil
}
func (r *FromUnixtime) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(r, len(children), 1)
}
return NewFromUnixtime(children[0]), nil
}
type CurrDate struct {
NoArgFunc
}
func (c CurrDate) IsNonDeterministic() bool {
return true
}
var _ sql.FunctionExpression = CurrDate{}
// Description implements sql.FunctionExpression
func (c CurrDate) Description() string {
return "returns the current date."
}
func NewCurrDate() sql.Expression {
return CurrDate{
NoArgFunc: NoArgFunc{"curdate", sql.LongText},
}
}
func NewCurrentDate() sql.Expression {
return CurrDate{
NoArgFunc: NoArgFunc{"current_date", sql.LongText},
}
}
func currDateLogic(ctx *sql.Context, _ sql.Row) (interface{}, error) {
t := ctx.QueryTime()
return fmt.Sprintf("%d-%02d-%02d", t.Year(), t.Month(), t.Day()), nil
}
// Eval implements sql.Expression
func (c CurrDate) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
return currDateLogic(ctx, row)
}
// WithChildren implements sql.Expression
func (c CurrDate) WithChildren(children ...sql.Expression) (sql.Expression, error) {
return NoArgFuncWithChildren(c, children)
}
// Determines the return type of a DateAdd/DateSub expression
// Logic is based on https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-add
func dateOffsetType(input sql.Expression, interval *expression.Interval) sql.Type {
if input == nil {
return sql.Null
}
inputType := input.Type()
// result is null if expression is null
if inputType == sql.Null {
return sql.Null
}
// set type flags
isInputDate := inputType == sql.Date
isInputTime := inputType == sql.Time
isInputDatetime := inputType == sql.Datetime || inputType == sql.Timestamp
// result is Datetime if expression is Datetime or Timestamp
if isInputDatetime {
return sql.Datetime
}
// determine what kind of interval we're dealing with
isYmdInterval := strings.Contains(interval.Unit, "YEAR") ||
strings.Contains(interval.Unit, "QUARTER") ||
strings.Contains(interval.Unit, "MONTH") ||
strings.Contains(interval.Unit, "WEEK") ||
strings.Contains(interval.Unit, "DAY")
isHmsInterval := strings.Contains(interval.Unit, "HOUR") ||
strings.Contains(interval.Unit, "MINUTE") ||
strings.Contains(interval.Unit, "SECOND")
isMixedInterval := isYmdInterval && isHmsInterval
// handle input of Date type
if isInputDate {
if isHmsInterval || isMixedInterval {
// if interval contains time components, result is Datetime
return sql.Datetime
} else {
// otherwise result is Date
return sql.Date
}
}
// handle input of Time type
if isInputTime {
if isYmdInterval || isMixedInterval {
// if interval contains date components, result is Datetime
return sql.Datetime
} else {
// otherwise result is Time
return sql.Time
}
}
// handle dynamic input type
if sql.IsDeferredType(inputType) {
if isYmdInterval && !isHmsInterval {
// if interval contains only date components, result is Date
return sql.Date
} else {
// otherwise result is Datetime
return sql.Datetime
}
}
// default type is VARCHAR
return sql.Text
}