src/org/redkale/service/DataSourceService.java

@@ -168,6 +168,36 @@ public class DataSourceService implements DataSource, Service, AutoCloseable {
         return source.find(clazz, selects, node);
     }
 
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable pk) {
+        return source.findColumn(clazz, column, pk);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final FilterBean bean) {
+        return source.findColumn(clazz, column, bean);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final FilterNode node) {
+        return source.findColumn(clazz, column, node);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final Serializable pk) {
+        return source.findColumn(clazz, column, defValue, pk);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final FilterBean bean) {
+        return source.findColumn(clazz, column, defValue, bean);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final FilterNode node) {
+        return source.findColumn(clazz, column, defValue, node);
+    }
+
     @Override
     public <T> boolean exists(final Class<T> clazz, final Serializable pk) {
         return source.exists(clazz, pk);

src/org/redkale/source/DataDefaultSource.java

@@ -1319,6 +1319,86 @@ public final class DataDefaultSource implements DataSource, Function<Class, Enti
         }
     }
 
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable pk) {
+        return findColumn(clazz, column, null, pk);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final FilterBean bean) {
+        return findColumn(clazz, column, null, FilterNodeBean.createFilterNode(bean));
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final FilterNode node) {
+        return findColumn(clazz, column, null, node);
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final Serializable pk) {
+        final EntityInfo<T> info = loadEntityInfo(clazz);
+        final EntityCache<T> cache = info.getCache();
+        if (cache != null) {
+            Serializable val = cache.findColumn(column, defValue, pk);
+            if (cache.isFullLoaded() || val != null) return val;
+        }
+
+        final Connection conn = createReadSQLConnection();
+        try {
+            final String sql = "SELECT " + info.getSQLColumn(null, column) + " FROM " + info.getTable(pk) + " WHERE " + info.getPrimarySQLColumn() + " = " + FilterNode.formatToString(pk);
+            if (debug.get() && info.isLoggable(Level.FINEST)) logger.finest(clazz.getSimpleName() + " find sql=" + sql);
+            final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            final ResultSet set = ps.executeQuery();
+            Serializable val = defValue;
+            if (set.next()) val = (Serializable) set.getObject(1);
+            set.close();
+            ps.close();
+            return val == null ? defValue : val;
+        } catch (SQLException sex) {
+            if (info.tableStrategy != null && info.tablenotexistSqlstates.contains(';' + sex.getSQLState() + ';')) return defValue;
+            throw new RuntimeException(sex);
+        } catch (Exception ex) {
+            throw new RuntimeException(ex);
+        } finally {
+            closeSQLConnection(conn);
+        }
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final FilterBean bean) {
+        return findColumn(clazz, column, defValue, FilterNodeBean.createFilterNode(bean));
+    }
+
+    @Override
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final FilterNode node) {
+        final EntityInfo<T> info = loadEntityInfo(clazz);
+        final EntityCache<T> cache = info.getCache();
+        if (cache != null && cache.isFullLoaded() && (node == null || node.isCacheUseable(this))) return cache.findColumn(column, defValue, node);
+
+        final Connection conn = createReadSQLConnection();
+        try {
+            final Map<Class, String> joinTabalis = node == null ? null : node.getJoinTabalis();
+            final CharSequence join = node == null ? null : node.createSQLJoin(this, false, joinTabalis, new HashSet<>(), info);
+            final CharSequence where = node == null ? null : node.createSQLExpress(info, joinTabalis);
+            final String sql = "SELECT " + info.getSQLColumn("a", column) + " FROM " + info.getTable(node) + " a" + (join == null ? "" : join) + ((where == null || where.length() == 0) ? "" : (" WHERE " + where));
+            if (debug.get() && info.isLoggable(Level.FINEST)) logger.finest(clazz.getSimpleName() + " find sql=" + sql);
+            final PreparedStatement ps = conn.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
+            final ResultSet set = ps.executeQuery();
+            Serializable val = defValue;
+            if (set.next()) val = (Serializable) set.getObject(1);
+            set.close();
+            ps.close();
+            return val == null ? defValue : val;
+        } catch (SQLException se) {
+            if (info.tableStrategy != null && info.tablenotexistSqlstates.contains(';' + se.getSQLState() + ';')) return defValue;
+            throw new RuntimeException(se);
+        } catch (Exception ex) {
+            throw new RuntimeException(ex);
+        } finally {
+            closeSQLConnection(conn);
+        }
+    }
+
     @Override
     public <T> boolean exists(Class<T> clazz, Serializable pk) {
         final EntityInfo<T> info = loadEntityInfo(clazz);

src/org/redkale/source/DataSource.java

@@ -126,6 +126,18 @@ public interface DataSource {
 
     public <T> T find(final Class<T> clazz, final SelectColumn selects, final FilterNode node);
 
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable pk);
+
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final FilterBean bean);
+
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final FilterNode node);
+
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final Serializable pk);
+
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final FilterBean bean);
+
+    public <T> Serializable findColumn(final Class<T> clazz, final String column, final Serializable defValue, final FilterNode node);
+
     public <T> boolean exists(final Class<T> clazz, final Serializable pk);
 
     public <T> boolean exists(final Class<T> clazz, final FilterBean bean);

src/org/redkale/source/EntityCache.java

@@ -138,6 +138,35 @@ public final class EntityCache<T> {
         return t;
     }
 
+    public Serializable findColumn(final String column, final Serializable defValue, final Serializable id) {
+        if (id == null) return defValue;
+        T rs = map.get(id);
+        if (rs == null) return defValue;
+        for (Attribute attr : this.info.attributes) {
+            if (column.equals(attr.field())) {
+                Serializable val = (Serializable) attr.get(rs);
+                return val == null ? defValue : val;
+            }
+        }
+        return defValue;
+    }
+
+    public Serializable findColumn(final String column, final Serializable defValue, FilterNode node) {
+        final Predicate<T> filter = node == null ? null : node.createPredicate(this);
+        Stream<T> stream = this.list.stream();
+        if (filter != null) stream = stream.filter(filter);
+        Optional<T> opt = stream.findFirst();
+        if (!opt.isPresent()) return defValue;
+        T rs = opt.get();
+        for (Attribute attr : this.info.attributes) {
+            if (column.equals(attr.field())) {
+                Serializable val = (Serializable) attr.get(rs);
+                return val == null ? defValue : val;
+            }
+        }
+        return defValue;
+    }
+
     public boolean exists(Serializable id) {
         if (id == null) return false;
         final Class atype = this.primary.type();