Apache calcite:将整数转换为日期时间

import org.apache.calcite.sql.type.SqlTypeFamily;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.calcite.sql.type.ReturnTypes;
import org.apache.calcite.sql.type.OperandTypes;
import org.apache.calcite.sql.SqlFunction;
import org.apache.calcite.sql.ScalarSqlFunction;
import org.apache.calcite.sql.type.SqlFunctionCategory;

public class IntToDate extends ScalarSqlFunction {

  public IntToDate() {
    super(
      "INT_TO_DATE",
      SqlKind.OTHER_FUNCTION,
      ReturnTypes.cascade(ReturnTypes.ARG0, SqlTypeFamily.DATE),
      OperandTypes.family(SqlTypeFamily.INTEGER, SqlTypeFamily.DATE),
      SqlFunctionCategory.SYSTEM);
  }
}

import org.apache.calcite.tools.RelBuilder;
import org.apache.calcite.tools.FrameworkConfig;
import org.apache.calcite.tools.Frameworks;

FrameworkConfig config = Frameworks.newConfigBuilder()
  .defaultSchema(schema)
  .build();

RelBuilder builder = RelBuilder.create(config);
builder.addCustomCalciteFunction(new IntToDate());

import org.apache.calcite.tools.RelBuilder;
import org.apache.calcite.rel.core.RelFactories;
import org.apache.calcite.rel.logical.LogicalAggregate;
import org.apache.calcite.rel.logical.LogicalProject;
import org.apache.calcite.rex.RexNode;
import org.apache.calcite.sql.type.SqlTypeName;

RelBuilder builder = ...; // 创建 RelBuilder 实例并注册自定义函数

int unixTimestamp = 1628696942; // 示例 UNIX 时间戳

RexNode intToDateTimeNode = builder.call(new IntToDate(), builder.literal(unixTimestamp));

RelBuilder.Config config = builder.config();
config.withRelBuilderFactory(RelFactories.LOGICAL_BUILDER);

LogicalProject project = builder.project(intToDateTimeNode).build();