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https://issues.apache.org/jira/browse/FLINK-26945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17703649#comment-17703649
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jackylau commented on FLINK-26945:
----------------------------------
I tried what you said, but it also didn't work . it will throws exception
ValidationException: Invalid argument type at position 0. Data type DATE
expected but STRING passed.
The reason is the implicit cast need supportsImplicitCast and StringToDate
should explicit
{code:java}
// code placeholder
class DateTimeArgumentTypeStrategy implements InputTypeStrategy {
@Override
public Optional<List<DataType>> inferInputTypes(
CallContext callContext, boolean throwOnFailure) {
List<DataType> argumentDataTypes = callContext.getArgumentDataTypes();
List<LogicalType> argumentTypes =
argumentDataTypes.stream()
.map(DataType::getLogicalType)
.collect(Collectors.toList());
LogicalType dateType = argumentTypes.get(0);
if (dateType.isAnyOf(LogicalTypeFamily.CHARACTER_STRING)
|| dateType.isAnyOf(
LogicalTypeRoot.TIMESTAMP_WITHOUT_TIME_ZONE,
LogicalTypeRoot.TIMESTAMP_WITH_LOCAL_TIME_ZONE)) {
argumentTypes.set(0, new DateType());
}
if (dateType.isAnyOf(LogicalTypeFamily.CHARACTER_STRING)
|| dateType.isAnyOf(
LogicalTypeRoot.TINYINT,
LogicalTypeRoot.SMALLINT,
LogicalTypeRoot.INTEGER)) {
argumentTypes.set(1, new IntType());
}
// TODO fail other types.
return Optional.of(
argumentTypes.stream()
.map(TypeConversions::fromLogicalToDataType)
.collect(Collectors.toList()));
}
}
{code}
> Add DATE_SUB supported in SQL & Table API
> -----------------------------------------
>
> Key: FLINK-26945
> URL: https://issues.apache.org/jira/browse/FLINK-26945
> Project: Flink
> Issue Type: Sub-task
> Components: Table SQL / API
> Reporter: dalongliu
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.17.0
>
>
> Returns the date {{numDays}} before {{{}startDate{}}}.
> Syntax:
> {code:java}
> date_sub(startDate, numDays) {code}
> Arguments:
> * {{{}startDate{}}}: A DATE expression.
> * {{{}numDays{}}}: An INTEGER expression.
> Returns:
> A DATE.
> If {{numDays}} is negative abs(num_days) are added to {{{}startDate{}}}.
> If the result date overflows the date range the function raises an error.
> Examples:
> {code:java}
> > SELECT date_sub('2016-07-30', 1);
> 2016-07-29 {code}
> See more:
> *
> [Spark|https://spark.apache.org/docs/latest/sql-ref-functions-builtin.html#date-and-timestamp-functions]
> * [Hive|https://cwiki.apache.org/confluence/display/hive/languagemanual+udf]
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