Qt 5.6 | Qt SQL | C++ Classes | QSqlRelation

Qt 5.6.2 Reference Documentation

# QSqlRelation Class

The QSqlRelation class stores information about an SQL foreign key. More...

Header: | #include <QSqlRelation>
qmake: | QT += sql

- List of all members, including inherited members

## Public Functions

| QSqlRelation()
| QSqlRelation(const QString &tableName, const QString &indexColumn, const QString &displayColumn)
QString | displayColumn() const
QString | indexColumn() const
bool | isValid() const
QString | tableName() const

## Detailed Description

The QSqlRelation class stores information about an SQL foreign key.

QSqlRelation is a helper class for QSqlRelationalTableModel. See QSqlRelationalTableModel::setRelation() and QSqlRelationalTableModel::relation() for details.

See also QSqlRelationalTableModel, QSqlRelationalDelegate, and Relational Table Model Example.

## Member Function Documentation

### QSqlRelation::QSqlRelation()

Constructs an invalid QSqlRelation object.

For such an object, the tableName(), indexColumn(), and displayColumn() functions return an empty string.

See also isValid().

### QSqlRelation::QSqlRelation(const QString &tableName, const QString &indexColumn, const QString &displayColumn)

Constructs a QSqlRelation object, where tableName is the SQL table name to which a foreign key refers, indexColumn is the foreign key, and displayColumn is the field that should be presented to the user.

See also tableName(), indexColumn(), and displayColumn().

### QString QSqlRelation::displayColumn() const

Returns the column from table tableName() that should be presented to the user instead of a foreign key.

### QString QSqlRelation::indexColumn() const

Returns the index column from table tableName() to which a foreign key refers.

### bool QSqlRelation::isValid() const

Returns `true` if the QSqlRelation object is valid; otherwise returns `false`.

### QString QSqlRelation::tableName() const

Returns the name of the table to which a foreign key refers.