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  **
  ** Copyright (C) 2016 The Qt Company Ltd.
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  ** This file is part of the QtSql module of the Qt Toolkit.
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  ****************************************************************************/
  
  #ifndef QSQLRELATIONALTABLEMODEL_H
  #define QSQLRELATIONALTABLEMODEL_H
  
  #include <QtSql/qsqltablemodel.h>
  
  QT_BEGIN_NAMESPACE
  
  
  class Q_SQL_EXPORT QSqlRelation
  {
  public:
      QSqlRelation() {}
      QSqlRelation(const QString &aTableName, const QString &indexCol,
                 const QString &displayCol)
          : tName(aTableName), iColumn(indexCol), dColumn(displayCol) {}
      inline QString tableName() const
      { return tName; }
      inline QString indexColumn() const
      { return iColumn; }
      inline QString displayColumn() const
      { return dColumn; }
      inline bool isValid() const
      { return !(tName.isEmpty() || iColumn.isEmpty() || dColumn.isEmpty()); }
  private:
      QString tName, iColumn, dColumn;
  };
  
  class QSqlRelationalTableModelPrivate;
  
  class Q_SQL_EXPORT QSqlRelationalTableModel: public QSqlTableModel
  {
      Q_OBJECT
  
  public:
      enum JoinMode {
          InnerJoin,
          LeftJoin
      };
  
      explicit QSqlRelationalTableModel(QObject *parent = Q_NULLPTR,
                                        QSqlDatabase db = QSqlDatabase());
      virtual ~QSqlRelationalTableModel();
  
      QVariant data(const QModelIndex &item, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE;
      bool setData(const QModelIndex &item, const QVariant &value, int role = Qt::EditRole) Q_DECL_OVERRIDE;
      bool removeColumns(int column, int count, const QModelIndex &parent = QModelIndex()) Q_DECL_OVERRIDE;
  
      void clear() Q_DECL_OVERRIDE;
      bool select() Q_DECL_OVERRIDE;
  
      void setTable(const QString &tableName) Q_DECL_OVERRIDE;
      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) Q_DECL_OVERRIDE;
  
  protected:
      QString selectStatement() const Q_DECL_OVERRIDE;
      bool updateRowInTable(int row, const QSqlRecord &values) Q_DECL_OVERRIDE;
      bool insertRowIntoTable(const QSqlRecord &values) Q_DECL_OVERRIDE;
      QString orderByClause() const Q_DECL_OVERRIDE;
  
  private:
      Q_DECLARE_PRIVATE(QSqlRelationalTableModel)
  };
  
  QT_END_NAMESPACE
  
  #endif // QSQLRELATIONALTABLEMODEL_H
  