Examples with DatastoreClass org.datanucleus.store.rdbms.table.DatastoreClass used on opensource projects

Example 21 with DatastoreClass

use of org.datanucleus.store.rdbms.table.DatastoreClass in project datanucleus-rdbms by datanucleus.

the class MapContainsValueMethod method containsAsJoin.

/**
 * Method to return an expression for Map.containsValue using INNER JOIN to the element.
 * This is only for use when there are no "!containsValue" and no "OR" operations.
 * Creates SQL by adding INNER JOIN to the join table (where it exists), and also to the value table
 * adding an AND condition on the value (with value of the valueExpr).
 * Returns a BooleanExpression "TRUE" (since the INNER JOIN will guarantee if the value is contained of not).
 * @param stmt SQLStatement
 * @param mapExpr Map expression
 * @param valExpr Expression for the value
 * @param joinType Type of join
 * @return Contains expression
 */
protected SQLExpression containsAsJoin(SQLStatement stmt, MapExpression mapExpr, SQLExpression valExpr, JoinType joinType) {
    boolean valIsUnbound = (valExpr instanceof UnboundExpression);
    String varName = null;
    String valAlias = null;
    if (valIsUnbound) {
        varName = ((UnboundExpression) valExpr).getVariableName();
        NucleusLogger.QUERY.debug("map.containsValue(" + valExpr + ") binding unbound variable " + varName + " using INNER JOIN");
    // TODO What if the variable is declared as a subtype, handle this see CollectionContainsMethod
    } else if (!stmt.getQueryGenerator().hasExplicitJoins()) {
        if (stmt.getJoinTypeForTable(valExpr.getSQLTable()) == JoinType.CROSS_JOIN) {
            // Value is currently joined via CROSS JOIN, so remove it (and use INNER JOIN below)
            valAlias = stmt.removeCrossJoin(valExpr.getSQLTable());
            valIsUnbound = true;
            NucleusLogger.QUERY.debug("map.containsValue(" + valExpr + ") was previously bound as CROSS JOIN but changing to INNER JOIN");
        }
    // TODO If owner is joined via CROSS JOIN and value is already present then remove CROSS JOIN
    // and join via INNER JOIN
    }
    RDBMSStoreManager storeMgr = stmt.getRDBMSManager();
    SQLExpressionFactory exprFactory = stmt.getSQLExpressionFactory();
    ClassLoaderResolver clr = stmt.getQueryGenerator().getClassLoaderResolver();
    AbstractMemberMetaData mmd = mapExpr.getJavaTypeMapping().getMemberMetaData();
    AbstractClassMetaData valCmd = mmd.getMap().getValueClassMetaData(clr);
    if (mmd.getMap().getMapType() == MapType.MAP_TYPE_JOIN) {
        // Map formed in join table - add join to join table, then to value table (if present)
        MapTable mapTbl = (MapTable) storeMgr.getTable(mmd);
        SQLTable joinSqlTbl = stmt.join(joinType, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping(), mapTbl, null, mapTbl.getOwnerMapping(), null, null);
        if (valCmd != null) {
            if (valIsUnbound) {
                DatastoreClass valTbl = storeMgr.getDatastoreClass(valCmd.getFullClassName(), clr);
                SQLTable valSqlTbl = stmt.join(joinType, joinSqlTbl, mapTbl.getValueMapping(), valTbl, valAlias, valTbl.getIdMapping(), null, null);
                // Bind the variable in the QueryGenerator
                valExpr = exprFactory.newExpression(stmt, valSqlTbl, valSqlTbl.getTable().getIdMapping());
                stmt.getQueryGenerator().bindVariable(varName, valCmd, valExpr.getSQLTable(), valExpr.getJavaTypeMapping());
            } else {
                // Add restrict to value
                SQLExpression valIdExpr = exprFactory.newExpression(stmt, joinSqlTbl, mapTbl.getValueMapping());
                stmt.whereAnd(valIdExpr.eq(valExpr), true);
            }
        } else {
            if (valIsUnbound) {
                // Bind the variable in the QueryGenerator
                valExpr = exprFactory.newExpression(stmt, joinSqlTbl, mapTbl.getValueMapping());
                stmt.getQueryGenerator().bindVariable(varName, null, valExpr.getSQLTable(), valExpr.getJavaTypeMapping());
            } else {
                // Add restrict to value
                SQLExpression valIdExpr = exprFactory.newExpression(stmt, joinSqlTbl, mapTbl.getValueMapping());
                stmt.whereAnd(valIdExpr.eq(valExpr), true);
            }
        }
    } else if (mmd.getMap().getMapType() == MapType.MAP_TYPE_KEY_IN_VALUE) {
        // Map formed in value table - add join to value table
        DatastoreClass valTbl = storeMgr.getDatastoreClass(valCmd.getFullClassName(), clr);
        JavaTypeMapping ownerMapping = null;
        if (mmd.getMappedBy() != null) {
            ownerMapping = valTbl.getMemberMapping(valCmd.getMetaDataForMember(mmd.getMappedBy()));
        } else {
            ownerMapping = valTbl.getExternalMapping(mmd, MappingType.EXTERNAL_FK);
        }
        SQLTable valSqlTbl = stmt.join(joinType, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping(), valTbl, valAlias, ownerMapping, null, null);
        if (valIsUnbound) {
            // Bind the variable in the QueryGenerator
            valExpr = exprFactory.newExpression(stmt, valSqlTbl, valTbl.getIdMapping());
            stmt.getQueryGenerator().bindVariable(varName, valCmd, valExpr.getSQLTable(), valExpr.getJavaTypeMapping());
        } else {
            // Add restrict to value
            SQLExpression valIdExpr = exprFactory.newExpression(stmt, valSqlTbl, valTbl.getIdMapping());
            stmt.whereAnd(valIdExpr.eq(valExpr), true);
        }
    } else if (mmd.getMap().getMapType() == MapType.MAP_TYPE_VALUE_IN_KEY) {
        // Map formed in key table - add join to key table then to value table
        AbstractClassMetaData keyCmd = mmd.getMap().getKeyClassMetaData(clr);
        DatastoreClass keyTbl = storeMgr.getDatastoreClass(keyCmd.getFullClassName(), clr);
        AbstractMemberMetaData keyValMmd = keyCmd.getMetaDataForMember(mmd.getValueMetaData().getMappedBy());
        JavaTypeMapping ownerMapping = null;
        if (mmd.getMappedBy() != null) {
            ownerMapping = keyTbl.getMemberMapping(keyCmd.getMetaDataForMember(mmd.getMappedBy()));
        } else {
            ownerMapping = keyTbl.getExternalMapping(mmd, MappingType.EXTERNAL_FK);
        }
        SQLTable keySqlTbl = stmt.join(joinType, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping(), keyTbl, null, ownerMapping, null, null);
        if (valCmd != null) {
            DatastoreClass valTbl = storeMgr.getDatastoreClass(valCmd.getFullClassName(), clr);
            SQLTable valSqlTbl = stmt.join(joinType, keySqlTbl, keyTbl.getMemberMapping(keyValMmd), valTbl, valAlias, valTbl.getIdMapping(), null, null);
            if (valIsUnbound) {
                // Bind the variable in the QueryGenerator
                valExpr = exprFactory.newExpression(stmt, valSqlTbl, valTbl.getIdMapping());
                stmt.getQueryGenerator().bindVariable(varName, valCmd, valExpr.getSQLTable(), valExpr.getJavaTypeMapping());
            } else {
                // Add restrict to value
                SQLExpression valIdExpr = exprFactory.newExpression(stmt, valSqlTbl, valTbl.getIdMapping());
                stmt.whereAnd(valIdExpr.eq(valExpr), true);
            }
        } else {
            if (valIsUnbound) {
                // Bind the variable in the QueryGenerator
                valExpr = exprFactory.newExpression(stmt, keySqlTbl, keyTbl.getMemberMapping(keyValMmd));
                stmt.getQueryGenerator().bindVariable(varName, null, valExpr.getSQLTable(), valExpr.getJavaTypeMapping());
            } else {
                // Add restrict to value
                SQLExpression valIdExpr = exprFactory.newExpression(stmt, keySqlTbl, keyTbl.getMemberMapping(keyValMmd));
                stmt.whereAnd(valIdExpr.eq(valExpr), true);
            }
        }
    }
    JavaTypeMapping m = exprFactory.getMappingForType(boolean.class, true);
    return exprFactory.newLiteral(stmt, m, true).eq(exprFactory.newLiteral(stmt, m, true));
}

Example 22 with DatastoreClass

use of org.datanucleus.store.rdbms.table.DatastoreClass in project datanucleus-rdbms by datanucleus.

the class MapGetMethod method getAsSubquery.

/**
 * Implementation of Map.get() using a subquery on the table representing the map,
 * adding a condition on the key and returning the value.
 * @param stmt SQLStatement
 * @param mapExpr The map expression
 * @param keyValExpr The key value expression
 * @return The value expression
 */
protected SQLExpression getAsSubquery(SQLStatement stmt, MapExpression mapExpr, SQLExpression keyValExpr) {
    ClassLoaderResolver clr = stmt.getQueryGenerator().getClassLoaderResolver();
    AbstractMemberMetaData mmd = mapExpr.getJavaTypeMapping().getMemberMetaData();
    MapMetaData mapmd = mmd.getMap();
    RDBMSStoreManager storeMgr = stmt.getRDBMSManager();
    JavaTypeMapping ownerMapping = null;
    JavaTypeMapping keyMapping = null;
    JavaTypeMapping valMapping = null;
    Table mapTbl = null;
    if (mapmd.getMapType() == MapType.MAP_TYPE_JOIN) {
        // JoinTable
        mapTbl = storeMgr.getTable(mmd);
        ownerMapping = ((MapTable) mapTbl).getOwnerMapping();
        keyMapping = ((MapTable) mapTbl).getKeyMapping();
        valMapping = ((MapTable) mapTbl).getValueMapping();
    } else if (mapmd.getMapType() == MapType.MAP_TYPE_KEY_IN_VALUE) {
        // ForeignKey from value table to key
        AbstractClassMetaData valCmd = mapmd.getValueClassMetaData(clr);
        mapTbl = storeMgr.getDatastoreClass(mmd.getMap().getValueType(), clr);
        if (mmd.getMappedBy() != null) {
            ownerMapping = mapTbl.getMemberMapping(valCmd.getMetaDataForMember(mmd.getMappedBy()));
        } else {
            ownerMapping = ((DatastoreClass) mapTbl).getExternalMapping(mmd, MappingType.EXTERNAL_FK);
        }
        String keyFieldName = mmd.getKeyMetaData().getMappedBy();
        AbstractMemberMetaData valKeyMmd = valCmd.getMetaDataForMember(keyFieldName);
        keyMapping = mapTbl.getMemberMapping(valKeyMmd);
        valMapping = mapTbl.getIdMapping();
    } else if (mapmd.getMapType() == MapType.MAP_TYPE_VALUE_IN_KEY) {
        // ForeignKey from key table to value
        AbstractClassMetaData keyCmd = mapmd.getKeyClassMetaData(clr);
        mapTbl = storeMgr.getDatastoreClass(mmd.getMap().getKeyType(), clr);
        if (mmd.getMappedBy() != null) {
            ownerMapping = mapTbl.getMemberMapping(keyCmd.getMetaDataForMember(mmd.getMappedBy()));
        } else {
            ownerMapping = ((DatastoreClass) mapTbl).getExternalMapping(mmd, MappingType.EXTERNAL_FK);
        }
        keyMapping = mapTbl.getIdMapping();
        String valFieldName = mmd.getValueMetaData().getMappedBy();
        AbstractMemberMetaData keyValMmd = keyCmd.getMetaDataForMember(valFieldName);
        valMapping = mapTbl.getMemberMapping(keyValMmd);
    } else {
        throw new NucleusException("Invalid map for " + mapExpr + " in get() call");
    }
    SelectStatement subStmt = new SelectStatement(stmt, storeMgr, mapTbl, null, null);
    SQLExpressionFactory exprFactory = stmt.getSQLExpressionFactory();
    subStmt.setClassLoaderResolver(clr);
    SQLExpression valExpr = exprFactory.newExpression(subStmt, subStmt.getPrimaryTable(), valMapping);
    subStmt.select(valExpr, null);
    // Link to primary statement
    SQLExpression elementOwnerExpr = exprFactory.newExpression(subStmt, subStmt.getPrimaryTable(), ownerMapping);
    SQLExpression ownerIdExpr = exprFactory.newExpression(stmt, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping());
    subStmt.whereAnd(elementOwnerExpr.eq(ownerIdExpr), true);
    // Condition on key
    SQLExpression keyExpr = exprFactory.newExpression(subStmt, subStmt.getPrimaryTable(), keyMapping);
    subStmt.whereAnd(keyExpr.eq(keyValExpr), true);
    SubqueryExpression subExpr = new SubqueryExpression(stmt, subStmt);
    subExpr.setJavaTypeMapping(valMapping);
    return subExpr;
}

Example 23 with DatastoreClass

use of org.datanucleus.store.rdbms.table.DatastoreClass in project datanucleus-rdbms by datanucleus.

the class MapGetMethod method getAsInnerJoin.

/**
 * Implementation of Map.get() using an inner join to the table representing the map, adding a condition on the key and returning the value.
 * @param stmt SQLStatement
 * @param mapExpr The map expression
 * @param keyValExpr The key value expression
 * @return The value expression
 */
protected SQLExpression getAsInnerJoin(SQLStatement stmt, MapExpression mapExpr, SQLExpression keyValExpr) {
    ClassLoaderResolver clr = stmt.getQueryGenerator().getClassLoaderResolver();
    SQLExpressionFactory exprFactory = stmt.getSQLExpressionFactory();
    JavaTypeMapping m = mapExpr.getJavaTypeMapping();
    AbstractMemberMetaData mmd = m.getMemberMetaData();
    if (mmd != null) {
        MapMetaData mapmd = mmd.getMap();
        if (mapmd.getMapType() == MapType.MAP_TYPE_JOIN) {
            MapTable joinTbl = (MapTable) stmt.getRDBMSManager().getTable(mmd);
            // Add join to join table
            SQLTable joinSqlTbl = stmt.join(JoinType.INNER_JOIN, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping(), joinTbl, null, joinTbl.getOwnerMapping(), null, null);
            // Add condition on key
            SQLExpression keyExpr = exprFactory.newExpression(stmt, joinSqlTbl, joinTbl.getKeyMapping());
            stmt.whereAnd(keyExpr.eq(keyValExpr), true);
            // Return value expression
            if (mapmd.getValueClassMetaData(clr) != null) {
                // Persistable value so join to its table
                DatastoreClass valTable = stmt.getRDBMSManager().getDatastoreClass(mapmd.getValueType(), clr);
                SQLTable valueSqlTbl = stmt.join(JoinType.INNER_JOIN, joinSqlTbl, joinTbl.getValueMapping(), valTable, null, valTable.getIdMapping(), null, null);
                return exprFactory.newExpression(stmt, valueSqlTbl, valTable.getIdMapping());
            }
            // Return mapping for the value in the join table
            SQLExpression valueExpr = exprFactory.newExpression(stmt, joinSqlTbl, joinTbl.getValueMapping());
            return valueExpr;
        } else if (mapmd.getMapType() == MapType.MAP_TYPE_KEY_IN_VALUE) {
            // Key stored in value table, so join to value table
            DatastoreClass valTable = stmt.getRDBMSManager().getDatastoreClass(mapmd.getValueType(), clr);
            AbstractClassMetaData valCmd = mapmd.getValueClassMetaData(clr);
            JavaTypeMapping mapTblOwnerMapping;
            if (mmd.getMappedBy() != null) {
                mapTblOwnerMapping = valTable.getMemberMapping(valCmd.getMetaDataForMember(mmd.getMappedBy()));
            } else {
                mapTblOwnerMapping = valTable.getExternalMapping(mmd, MappingType.EXTERNAL_FK);
            }
            SQLTable valSqlTbl = stmt.join(JoinType.INNER_JOIN, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping(), valTable, null, mapTblOwnerMapping, null, null);
            // Add condition on key
            JavaTypeMapping keyMapping = valTable.getMemberMapping(valCmd.getMetaDataForMember(mmd.getKeyMetaData().getMappedBy()));
            SQLExpression keyExpr = exprFactory.newExpression(stmt, valSqlTbl, keyMapping);
            stmt.whereAnd(keyExpr.eq(keyValExpr), true);
            // Return value expression
            SQLExpression valueExpr = exprFactory.newExpression(stmt, valSqlTbl, valTable.getIdMapping());
            return valueExpr;
        } else if (mapmd.getMapType() == MapType.MAP_TYPE_VALUE_IN_KEY) {
            // Value stored in key table, so join to key table
            DatastoreClass keyTable = stmt.getRDBMSManager().getDatastoreClass(mapmd.getKeyType(), clr);
            AbstractClassMetaData keyCmd = mapmd.getKeyClassMetaData(clr);
            JavaTypeMapping mapTblOwnerMapping;
            if (mmd.getMappedBy() != null) {
                mapTblOwnerMapping = keyTable.getMemberMapping(keyCmd.getMetaDataForMember(mmd.getMappedBy()));
            } else {
                mapTblOwnerMapping = keyTable.getExternalMapping(mmd, MappingType.EXTERNAL_FK);
            }
            SQLTable keySqlTbl = stmt.join(JoinType.INNER_JOIN, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping(), keyTable, null, mapTblOwnerMapping, null, null);
            // Add condition on key
            SQLExpression keyExpr = exprFactory.newExpression(stmt, keySqlTbl, keyTable.getIdMapping());
            stmt.whereAnd(keyExpr.eq(keyValExpr), true);
            // Return value expression
            JavaTypeMapping valueMapping = keyTable.getMemberMapping(keyCmd.getMetaDataForMember(mmd.getValueMetaData().getMappedBy()));
            SQLExpression valueExpr = exprFactory.newExpression(stmt, keySqlTbl, valueMapping);
            return valueExpr;
        }
    }
    throw new NucleusException("Map.get() for the filter is not supported for " + mapExpr + " with an argument of " + keyValExpr + ". Why not contribute support for it?");
}

Example 24 with DatastoreClass

use of org.datanucleus.store.rdbms.table.DatastoreClass in project datanucleus-rdbms by datanucleus.

the class MapValueMethod method getAsJoin.

/**
 * Implementation of VALUE(map) using a join to the table representing the map, and returning the value.
 * @param stmt SQLStatement
 * @param mapExpr The map expression
 * @return The value expression
 */
protected SQLExpression getAsJoin(SQLStatement stmt, MapExpression mapExpr) {
    JavaTypeMapping m = mapExpr.getJavaTypeMapping();
    RDBMSStoreManager storeMgr = stmt.getRDBMSManager();
    ClassLoaderResolver clr = stmt.getQueryGenerator().getClassLoaderResolver();
    SQLExpressionFactory exprFactory = stmt.getSQLExpressionFactory();
    AbstractMemberMetaData mmd = m.getMemberMetaData();
    // Use the statement of the table for this Map expression, since it could be in an outer query
    stmt = mapExpr.getSQLTable().getSQLStatement();
    if (mmd != null) {
        MapMetaData mapmd = mmd.getMap();
        SQLTable mapSqlTbl = mapExpr.getSQLTable();
        // Set alias of "map" table from MapExpression in case it was defined in FROM clause
        String mapJoinAlias = mapExpr.getAliasForMapTable();
        if (mapJoinAlias == null) {
            mapJoinAlias = (mapExpr.getSQLTable().getAlias().toString() + "_" + mmd.getName()).toUpperCase();
        }
        if (mapmd.getMapType() == MapType.MAP_TYPE_JOIN) {
            // Add join to join table
            MapTable joinTbl = (MapTable) storeMgr.getTable(mmd);
            SQLTable joinSqlTbl = stmt.getTable(mapJoinAlias);
            if (joinSqlTbl == null) {
                joinSqlTbl = stmt.join(JoinType.INNER_JOIN, mapSqlTbl, mapSqlTbl.getTable().getIdMapping(), joinTbl, mapJoinAlias, joinTbl.getOwnerMapping(), null, null);
            }
            // Return value expression
            if (mapmd.getValueClassMetaData(clr) != null && !mapmd.isEmbeddedValue()) {
                // Persistable value so join to its table (default to "{mapJoinAlias}_VALUE")
                DatastoreClass valTable = storeMgr.getDatastoreClass(mapmd.getValueType(), clr);
                SQLTable valueSqlTbl = stmt.getTable(mapJoinAlias + "_VALUE");
                if (valueSqlTbl == null) {
                    valueSqlTbl = stmt.join(JoinType.INNER_JOIN, joinSqlTbl, joinTbl.getValueMapping(), valTable, mapJoinAlias + "_VALUE", valTable.getIdMapping(), null, null);
                }
                return exprFactory.newExpression(stmt, valueSqlTbl, valTable.getIdMapping());
            }
            return exprFactory.newExpression(stmt, joinSqlTbl, joinTbl.getValueMapping());
        } else if (mapmd.getMapType() == MapType.MAP_TYPE_KEY_IN_VALUE) {
            // Key stored in value table, so join to value table
            DatastoreClass valTable = storeMgr.getDatastoreClass(mapmd.getValueType(), clr);
            AbstractClassMetaData valCmd = mmd.getMap().getValueClassMetaData(clr);
            JavaTypeMapping mapTblOwnerMapping;
            if (mmd.getMappedBy() != null) {
                mapTblOwnerMapping = valTable.getMemberMapping(valCmd.getMetaDataForMember(mmd.getMappedBy()));
            } else {
                mapTblOwnerMapping = valTable.getExternalMapping(mmd, MappingType.EXTERNAL_FK);
            }
            SQLTable valSqlTbl = stmt.join(JoinType.INNER_JOIN, mapSqlTbl, mapSqlTbl.getTable().getIdMapping(), valTable, mapJoinAlias, mapTblOwnerMapping, null, null);
            // Return value expression
            return exprFactory.newExpression(stmt, valSqlTbl, valTable.getIdMapping());
        } else if (mapmd.getMapType() == MapType.MAP_TYPE_VALUE_IN_KEY) {
            // Value stored in key table, so join to key table
            DatastoreClass keyTable = storeMgr.getDatastoreClass(mapmd.getKeyType(), clr);
            AbstractClassMetaData keyCmd = mmd.getMap().getKeyClassMetaData(clr);
            JavaTypeMapping mapTblOwnerMapping;
            if (mmd.getMappedBy() != null) {
                mapTblOwnerMapping = keyTable.getMemberMapping(keyCmd.getMetaDataForMember(mmd.getMappedBy()));
            } else {
                mapTblOwnerMapping = keyTable.getExternalMapping(mmd, MappingType.EXTERNAL_FK);
            }
            SQLTable keySqlTbl = stmt.join(JoinType.INNER_JOIN, mapSqlTbl, mapSqlTbl.getTable().getIdMapping(), keyTable, mapJoinAlias, mapTblOwnerMapping, null, null);
            // Return value expression
            AbstractMemberMetaData valKeyMmd = mapmd.getKeyClassMetaData(clr).getMetaDataForMember(mmd.getValueMetaData().getMappedBy());
            JavaTypeMapping valueMapping = keyTable.getMemberMapping(valKeyMmd);
            return exprFactory.newExpression(stmt, keySqlTbl, valueMapping);
        }
    }
    throw new NucleusException("KEY(map) for the filter is not supported for " + mapExpr + ". Why not contribute support for it?");
}

Example 25 with DatastoreClass

use of org.datanucleus.store.rdbms.table.DatastoreClass in project datanucleus-rdbms by datanucleus.

the class MapValueMethod method getAsSubquery.

/**
 * Implementation of VALUE(map) using a subquery on the table representing the map, returning the value.
 * @param stmt SQLStatement
 * @param mapExpr The map expression
 * @return The value expression
 */
protected SQLExpression getAsSubquery(SQLStatement stmt, MapExpression mapExpr) {
    AbstractMemberMetaData mmd = mapExpr.getJavaTypeMapping().getMemberMetaData();
    MapMetaData mapmd = mmd.getMap();
    RDBMSStoreManager storeMgr = stmt.getRDBMSManager();
    ClassLoaderResolver clr = stmt.getQueryGenerator().getClassLoaderResolver();
    JavaTypeMapping ownerMapping = null;
    JavaTypeMapping valMapping = null;
    Table mapTbl = null;
    if (mapmd.getMapType() == MapType.MAP_TYPE_JOIN) {
        // JoinTable
        mapTbl = storeMgr.getTable(mmd);
        ownerMapping = ((MapTable) mapTbl).getOwnerMapping();
        valMapping = ((MapTable) mapTbl).getValueMapping();
    } else if (mapmd.getMapType() == MapType.MAP_TYPE_KEY_IN_VALUE) {
        // ForeignKey from value table to key
        AbstractClassMetaData valCmd = mapmd.getValueClassMetaData(clr);
        mapTbl = storeMgr.getDatastoreClass(mmd.getMap().getValueType(), clr);
        if (mmd.getMappedBy() != null) {
            ownerMapping = mapTbl.getMemberMapping(valCmd.getMetaDataForMember(mmd.getMappedBy()));
        } else {
            ownerMapping = ((DatastoreClass) mapTbl).getExternalMapping(mmd, MappingType.EXTERNAL_FK);
        }
        valMapping = mapTbl.getIdMapping();
    } else if (mapmd.getMapType() == MapType.MAP_TYPE_VALUE_IN_KEY) {
        // ForeignKey from key table to value
        AbstractClassMetaData keyCmd = mapmd.getKeyClassMetaData(clr);
        mapTbl = storeMgr.getDatastoreClass(mmd.getMap().getKeyType(), clr);
        if (mmd.getMappedBy() != null) {
            ownerMapping = mapTbl.getMemberMapping(keyCmd.getMetaDataForMember(mmd.getMappedBy()));
        } else {
            ownerMapping = ((DatastoreClass) mapTbl).getExternalMapping(mmd, MappingType.EXTERNAL_FK);
        }
        String valFieldName = mmd.getValueMetaData().getMappedBy();
        AbstractMemberMetaData keyValMmd = keyCmd.getMetaDataForMember(valFieldName);
        valMapping = mapTbl.getMemberMapping(keyValMmd);
    } else {
        throw new NucleusException("Invalid map for " + mapExpr + " in get() call");
    }
    SQLExpressionFactory exprFactory = stmt.getSQLExpressionFactory();
    SelectStatement subStmt = new SelectStatement(stmt, storeMgr, mapTbl, null, null);
    subStmt.setClassLoaderResolver(clr);
    SQLExpression valExpr = exprFactory.newExpression(subStmt, subStmt.getPrimaryTable(), valMapping);
    subStmt.select(valExpr, null);
    // Link to primary statement
    SQLExpression elementOwnerExpr = exprFactory.newExpression(subStmt, subStmt.getPrimaryTable(), ownerMapping);
    SQLExpression ownerIdExpr = exprFactory.newExpression(stmt, mapExpr.getSQLTable(), mapExpr.getSQLTable().getTable().getIdMapping());
    subStmt.whereAnd(elementOwnerExpr.eq(ownerIdExpr), true);
    SubqueryExpression subExpr = new SubqueryExpression(stmt, subStmt);
    subExpr.setJavaTypeMapping(valMapping);
    return subExpr;
}