Hive 功能：添加月份到日期

Posted 2023-04-18

【中文标题】Hive 功能：添加月份到日期

【英文标题】：Hive function: add month to date

【发布时间】：2014-12-19 14:18:52

【问题描述】：

我正在 Hive 中搜索一个函数，它将添加月份至今。

例如：

add_month('2014-01-01',1) -> '2014-02-01'
add_month('2013-12-01',1) -> '2014-01-01'

【问题讨论】：

如果在 1 月 31 日加上 1 个月会怎样？

我的情况比较简单，我总是需要在月份的第一天加上1个月，例如：2014-01-01 -> 2014-02-01； 2013-12-01 -> 2014-01-01

在标准 SQL 中，这将是 date '2014-01-01' + interval '1' month。不知道 Hive 是否支持 SQL 标准。

【参考方案1】：

只需输入：

 select add_months('2014-01-01', 1);

【参考方案2】：

您可以创建通用 UDF (GenericUDF)。

这是一个示例 UDF：

import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.IntObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.StringObjectInspector;
import org.joda.time.LocalDate;
import org.joda.time.format.DateTimeFormat;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;

public class AddMonth extends GenericUDF 

    @Override
    public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException 
        if (arguments.length != 2) 
            throw new UDFArgumentLengthException("The function add_month(local_date, months_to_add) requires 2 arguments.");
        

        ObjectInspector localDateVal = arguments[0];
        ObjectInspector monthsToAddVal = arguments[1];

        if (!(localDateVal instanceof StringObjectInspector)) 
            throw new UDFArgumentException("First argument must be of type String (local_date as String)");
        
        if (!(monthsToAddVal instanceof IntObjectInspector)) 
            throw new UDFArgumentException("Second argument must be of type int (Month to add)");
        
        return PrimitiveObjectInspectorFactory.writableStringObjectInspector;
    

    @Override
    public Object evaluate(DeferredObject[] arguments) throws HiveException 
        String localDateVal = (String) ObjectInspectorUtils.copyToStandardJavaObject(arguments[0].get(),
                PrimitiveObjectInspectorFactory.javaStringObjectInspector);
        IntWritable monthsToAddVal = (IntWritable) ObjectInspectorUtils.copyToStandardJavaObject(arguments[1].get(),
                PrimitiveObjectInspectorFactory.javaIntObjectInspector);

        LocalDate localDate = null;
        try 
            localDate = LocalDate.parse(localDateVal, DateTimeFormat.forPattern("yyyy-MM-dd"));
         catch (Exception ex) 
            return null;
        

        return new Text(localDate.plusMonths(monthsToAddVal.get().toString());
    

    @Override
    public String getDisplayString(String[] arguments) 
        assert (arguments.length == 2);
        return "add_month(" + arguments[0] + ", " + arguments[1] + ")";
    

证明正确性的测试用例：

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertThat;

import org.apache.hadoop.hive.ql.udf.generic.GenericUDF.DeferredJavaObject;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF.DeferredObject;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.junit.Test;

public class AddMonthTest 
    private final String TEST_DATA = "2014-01-01";
    private final AddMonth addMonth = new AddMonth();
    ObjectInspector ob = PrimitiveObjectInspectorFactory.javaStringObjectInspector;
    ObjectInspector ob1 = PrimitiveObjectInspectorFactory.javaIntObjectInspector;
    private final ObjectInspector[]arg =  ob, ob1 ;

    @Test
    public void testAdd1Month() throws Exception 
        DeferredJavaObject def1 = new DeferredJavaObject(TEST_DATA);
        DeferredJavaObject def2 = new DeferredJavaObject(1);

        addMonth.initialize(arg);

        DeferredObject[] def =  def1, def2 ;
        String resultData = addMonth.evaluate(def).toString();
        assertThat(resultData, is("2014-02-01"));
    

    @Test
    public void testAdd12Month() throws Exception 
        DeferredJavaObject def1 = new DeferredJavaObject(TEST_DATA);
        DeferredJavaObject def2 = new DeferredJavaObject(12);

        addMonth.initialize(arg);

        DeferredObject[] def =  def1, def2 ;
        String resultData = addMonth.evaluate(def).toString();
        assertThat(resultData, is("2015-01-01"));
    

    @Test
    public void testSub1Month() throws Exception 
        DeferredJavaObject def1 = new DeferredJavaObject(TEST_DATA);
        DeferredJavaObject def2 = new DeferredJavaObject(-1);

        addMonth.initialize(arg);

        DeferredObject[] def =  def1, def2 ;
        String resultData = addMonth.evaluate(def).toString();
        assertThat(resultData, is("2013-12-01"));
    

    @Test
    public void testSub12Month() throws Exception 
        DeferredJavaObject def1 = new DeferredJavaObject(TEST_DATA);
        DeferredJavaObject def2 = new DeferredJavaObject(-12);

        addMonth.initialize(arg);

        DeferredObject[] def =  def1, def2 ;
        String resultData = addMonth.evaluate(def).toString();
        assertThat(resultData, is("2013-01-01"));
    

    @Test
    public void incorrectInput() throws Exception 
        DeferredJavaObject def1 = new DeferredJavaObject("InvalidString");
        DeferredJavaObject def2 = new DeferredJavaObject(12);

        addMonth.initialize(arg);

        DeferredObject[] def =  def1, def2 ;
        Object resultData = addMonth.evaluate(def);
        assertNull(resultData);
    

你可以使用如下函数：

CREATE TEMPORARY FUNCTION add_month AS 'AddMonth';

SELECT
    add_month ('2014-01-01',1) 
FROM
    TAB_NAME;

预期输出将是：

2014-02-01

【讨论】：

我在转换为 Text 和 writableInt 时不断出错。有什么提示吗？

你可以使用 add_months 请看这个：***.com/questions/38221393/…