return nil, err
	}
	ts1, ok := tval1.ToTimestamp()
	if !ok {
		return nil, fmt.Errorf("%s() expects two timestamp arguments", sqlFnDateDiff)
	}

	tval2, err := d.Timestamp2.evalNode(r, tableAlias)
	if err != nil {
		return nil, err
	}
	if err = inferTypeAsTimestamp(tval2); err != nil {
		return nil, err
	}
	ts2, ok := tval2.ToTimestamp()
	if !ok {

// conversion succeeded.
func (v Value) ToBool() (val bool, ok bool) {
	val, ok = v.value.(bool)
	return val, ok
}

// ToTimestamp returns the timestamp value if present.
func (v Value) ToTimestamp() (t time.Time, ok bool) {
	t, ok = v.value.(time.Time)
	return t, ok
}

// ToBytes returns the value if byte-slice.
func (v Value) ToBytes() (val []byte, ok bool) {

        <plugin>
          <artifactId>maven-javadoc-plugin</artifactId>
          <version>${maven-javadoc-plugin.version}</version>
          <configuration>
            <quiet>true</quiet>
            <notimestamp>true</notimestamp>
            <encoding>UTF-8</encoding>
            <docencoding>UTF-8</docencoding>
            <charset>UTF-8</charset>
            <additionalOptions>

        <plugin>
          <artifactId>maven-javadoc-plugin</artifactId>
          <version>${maven-javadoc-plugin.version}</version>
          <configuration>
            <quiet>true</quiet>
            <notimestamp>true</notimestamp>
            <encoding>UTF-8</encoding>
            <docencoding>UTF-8</docencoding>
            <charset>UTF-8</charset>
            <additionalOptions>