SELECT CASE WHEN THEN ELSE END AS

方法一：SELECT CASE WHEN SUBSTRING(timerange, LENGTH(timerange)) < "5"            THEN CONCAT(SUBSTRING(timerange, 1, LENGTH(timerange) - 1), "0")            ELSE CONCAT(SUBSTRING(timerange, 1, LENGTH(timerange) - 1), "5")       END AS timerangeFROM Employee;方法二：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;public class TimeRangeConverter GenericUDF {    @Override    public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {        if (arguments.length != 1) {            throw new UDFArgumentLengthException("The function time_range_converter(time_rage) requires 1 argument.");        }        ObjectInspector timeRangeVal = arguments[0];        if (!(timeRangeVal instanceof StringObjectInspector)) {            throw new UDFArgumentException("First argument must be of type String (time_range as String)");        }        return PrimitiveObjectInspectorFactory.writableStringObjectInspector;    }    @Override    public Object evaluate(DeferredObject[] arguments) throws HiveException {        String timeRangeVal = (String) ObjectInspectorUtils.copyToStandardJavaObject(arguments[0].get(),                PrimitiveObjectInspectorFactory.javaStringObjectInspector);        char[] characters = timeRangeVal.toCharArray();        if (characters[characters.length - 1] > '5') {            characters[characters.length - 1] = '5';        } else {            characters[characters.length - 1] = '0';        }        return String.valueOf(characters);    }    @Override    public String getDisplayString(String[] arguments) {        assert (arguments.length == 1);        return "time_range_converter(" + arguments[0] + ")";    }}Call the Hive update statement like:CREATE TEMPORARY FUNCTION time_range_converterAS 'TimeRangeConverter';UPDATE     Employee SET     timerange = time_range_converter(timerange);