org.hibernate.MappingException: Could not determine type for: String, at table: Elec_SystemDDL, for

org.hibernate.MappingException: Could not determine type for: String, at table: Elec_SystemDDL, for columns: [org.hibernate.mapping.Column(ddlName)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="cn.itcast.elec.domain.ElecSystemDDl" table="Elec_SystemDDL">
        <id name="seqID" type="integer">
            <column name="seqID" not-null="true"  />
            <generator class="increment"></generator>
        </id>
        <property name="keyWord" type="string">
            <column name="Keyword" />
        </property>
        <property name="ddlCode" type="integer">
            <column name="ddlCode"/>
        </property>

        <property name="ddlName" type="String">
            <column name="ddlName" />
        </property>
    </class>
</hibernate-mapping>

org.hibernate.MappingException: Could not determine type for: Integer, at table: Elec_SystemDDL, for columns: [org.hibernate.mapping.Column(ddlCode)]
    org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:291)