Fixed behavior on NULL foreign keys

Instead of using a simple INNER JOIN, like:

SELECT a,b,rel.c FROM table1, table2 WHERE (table1.smthing =
table2.smthing)

which doesn't show row where foreign keys are NULL, allow use of LEFT
JOIN like:

SELECT a,b,rel.c FROM table1 LEFT JOIN table2 ON table1.smthing =
table2.smthing

The trick works also for multi-relational tables.
Just remember to use the new API setJoinMode.

Signed-off-by: DaNiMoTh <jjdanimoth@gmail.com>

Change-Id: I349f9418e4859923977942add59872b000cac2c5
Task-number:QTBUG-8217
Reviewed-by:Michael Goddard
Reviewed-by:Charles Yin

Merge-request: 2576
Reviewed-by: Charles Yin <charles.yin@nokia.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/sql/models/qsqlrelationaltablemodel.h b/src/sql/models/qsqlrelationaltablemodel.h
index 15faae9b57..32d88b3189 100644
--- a/src/sql/models/qsqlrelationaltablemodel.h
+++ b/src/sql/models/qsqlrelationaltablemodel.h
@@ -76,6 +76,11 @@ class Q_SQL_EXPORT QSqlRelationalTableModel: public QSqlTableModel
     Q_OBJECT
 
 public:
+    enum JoinMode {
+        InnerJoin,
+        LeftJoin
+    };
+
     explicit QSqlRelationalTableModel(QObject *parent = 0,
                                       QSqlDatabase db = QSqlDatabase());
     virtual ~QSqlRelationalTableModel();
@@ -91,6 +96,7 @@ public:
     virtual void setRelation(int column, const QSqlRelation &relation);
     QSqlRelation relation(int column) const;
     virtual QSqlTableModel *relationModel(int column) const;
+    void setJoinMode( QSqlRelationalTableModel::JoinMode joinMode );
 
 public Q_SLOTS:
     void revertRow(int row);