4 files changed, 53 insertions, 20 deletions

diff --git a/src/sql/kernel/qsqldatabase.cpp b/src/sql/kernel/qsqldatabase.cpp
index da5c51e770..fdbb16a589 100644
--- a/src/sql/kernel/qsqldatabase.cpp
+++ b/src/sql/kernel/qsqldatabase.cpp
@@ -7,6 +7,7 @@
 #include "qcoreapplication.h"
 #include "qreadwritelock.h"
 #include "qsqldriver.h"
+#include "qsqldriver_p.h"
 #include "qsqldriverplugin.h"
 #include "qsqlindex.h"
 #include "QtCore/qapplicationstatic.h"
@@ -122,7 +123,7 @@ QSqlDatabasePrivate::~QSqlDatabasePrivate()
 QtSqlGlobals::~QtSqlGlobals()
 {
     qDeleteAll(registeredDrivers);
-    for (const auto &[k, v] : connections.asKeyValueRange())
+    for (const auto &[k, v] : std::as_const(connections).asKeyValueRange())
         QSqlDatabasePrivate::invalidateDb(v, k, false);
 }
 
@@ -282,6 +283,10 @@ void QSqlDatabasePrivate::disable()
     QSqlDriver.  Alternatively, you can subclass your own database
     driver from QSqlDriver. See \l{How to Write Your Own Database
     Driver} for more information.
+    A QSqlDatabase instance must only be accessed by the thread it
+    was created in. Therefore you have to make sure to create them
+    in the correct context. Alternatively you can change the context
+    with QSqlDatabase::moveToThread().
 
     Create a connection (i.e., an instance of QSqlDatabase) by calling
     one of the static addDatabase() functions, where you specify
@@ -1333,6 +1338,50 @@ QSql::NumericalPrecisionPolicy QSqlDatabase::numericalPrecisionPolicy() const
         return d->precisionPolicy;
 }
 
+/*!
+    \since 6.8
+
+    Changes the thread affinity for QSqlDatabase and its associated driver.
+    This function returns \c true when the function succeeds. Event processing
+    will continue in the \a targetThread.
+
+    During this operation you have to make sure that there is no QSqlQuery
+    bound to this instance otherwise the QSqlDatabase will not be moved to
+    the given thread and the function returns \c false.
+
+    Since the associated driver is derived from QObject, all constraints for
+    moving a QObject to another thread also apply to this function.
+
+    \sa QObject::moveToThread(), {Threads and the SQL Module}
+*/
+bool QSqlDatabase::moveToThread(QThread *targetThread)
+{
+    if (auto drv = driver()) {
+        if (drv != QSqlDatabasePrivate::shared_null()->driver) {
+            // two instances are alive - the one here and the one in dbDict()
+            if (d->ref.loadRelaxed() > 2) {
+                qWarning("QSqlDatabasePrivate::moveToThread: connection '%ls' is still in use "
+                         "in the current thread.", qUtf16Printable(d->connName));
+                return false;
+            }
+            return drv->moveToThread(targetThread);
+        }
+    }
+    return false;
+}
+
+/*!
+    \since 6.8
+
+    Returns a pointer to the associated QThread instance.
+*/
+QThread *QSqlDatabase::currentThread() const
+{
+    if (auto drv = driver())
+        return drv->thread();
+    return nullptr;
+}
+
 
 #ifndef QT_NO_DEBUG_STREAM
 QDebug operator<<(QDebug dbg, const QSqlDatabase &d)
diff --git a/src/sql/kernel/qsqldatabase.h b/src/sql/kernel/qsqldatabase.h
index 10019c7d5c..5059dbba83 100644
--- a/src/sql/kernel/qsqldatabase.h
+++ b/src/sql/kernel/qsqldatabase.h
@@ -18,6 +18,7 @@ class QSqlIndex;
 class QSqlRecord;
 class QSqlQuery;
 class QSqlDatabasePrivate;
+class QThread;
 
 class Q_SQL_EXPORT QSqlDriverCreatorBase
 {
@@ -80,6 +81,8 @@ public:
     QString connectionName() const;
     void setNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy precisionPolicy);
     QSql::NumericalPrecisionPolicy numericalPrecisionPolicy() const;
+    bool moveToThread(QThread *targetThread);
+    QThread *currentThread() const;
 
     QSqlDriver* driver() const;
 
diff --git a/src/sql/kernel/qsqlindex.cpp b/src/sql/kernel/qsqlindex.cpp
index 26553155cc..15ee489928 100644
--- a/src/sql/kernel/qsqlindex.cpp
+++ b/src/sql/kernel/qsqlindex.cpp
@@ -149,24 +149,6 @@ void QSqlIndex::setDescending(int i, bool desc)
         sorts[i] = desc;
 }
 
-/*! \internal
-
-  Creates a string representing the field number \a i using prefix \a
-  prefix. If \a verbose is true, ASC or DESC is included in the field
-  description if the field is sorted in ASCending or DESCending order.
-*/
-
-QString QSqlIndex::createField(int i, const QString& prefix, bool verbose) const
-{
-    QString f;
-    if (!prefix.isEmpty())
-        f += prefix + u'.';
-    f += field(i).name();
-    if (verbose)
-        f += u' ' + QString((isDescending(i) ? "DESC"_L1 : "ASC"_L1));
-    return f;
-}
-
 /*!
     \property QSqlIndex::cursorName
     \since 6.8
diff --git a/src/sql/kernel/qsqlindex.h b/src/sql/kernel/qsqlindex.h
index 409cb463e3..3d5d95b373 100644
--- a/src/sql/kernel/qsqlindex.h
+++ b/src/sql/kernel/qsqlindex.h
@@ -47,7 +47,6 @@ public:
     void setDescending(int i, bool desc);
 
 private:
-    QString createField(int i, const QString& prefix, bool verbose) const;
     // ### Qt7: move to d-ptr
     QString cursor;
     QString nm;