mssql provider: improve datetime support (fixes #12461)

(cherry-picked from 018cdd2)

Author: jef-n

src/providers/mssql/qgsmssqlprovider.cpp

@@ -311,16 +311,16 @@ QVariant::Type QgsMssqlProvider::DecodeSqlType( QString sqlTypeName )
   {
     type = QVariant::ByteArray;
   }
-  else if ( sqlTypeName.startsWith( "date", Qt::CaseInsensitive ) )
-  {
-    type = QVariant::Date;
-  }
   else if ( sqlTypeName.startsWith( "datetime", Qt::CaseInsensitive ) ||
             sqlTypeName.startsWith( "smalldatetime", Qt::CaseInsensitive ) ||
             sqlTypeName.startsWith( "datetime2", Qt::CaseInsensitive ) )
   {
     type = QVariant::DateTime;
   }
+  else if ( sqlTypeName.startsWith( "date", Qt::CaseInsensitive ) )
+  {
+    type = QVariant::Date;
+  }
   else if ( sqlTypeName.startsWith( "time", Qt::CaseInsensitive ) ||
             sqlTypeName.startsWith( "timestamp", Qt::CaseInsensitive ) )
   {
@@ -879,6 +879,21 @@ bool QgsMssqlProvider::addFeatures( QgsFeatureList & flist )
         // binding a TEXT value
         query.addBindValue( attrs[i].toString() );
       }
+      else if ( type == QVariant::Time )
+      {
+        // binding a TIME value
+        query.addBindValue( attrs[i].toTime().toString( Qt::ISODate ) );
+      }
+      else if ( type == QVariant::Date )
+      {
+        // binding a DATE value
+        query.addBindValue( attrs[i].toDate().toString( Qt::ISODate ) );
+      }
+      else if ( type == QVariant::DateTime )
+      {
+        // binding a DATETIME value
+        query.addBindValue( attrs[i].toDateTime().toString( Qt::ISODate ) );
+      }
       else
       {
         query.addBindValue( attrs[i] );
@@ -1119,6 +1134,21 @@ bool QgsMssqlProvider::changeAttributeValues( const QgsChangedAttributesMap &att
         // binding a TEXT value
         query.addBindValue( it2->toString() );
       }
+      else if ( type == QVariant::DateTime )
+      {
+        // binding a DATETIME value
+        query.addBindValue( it2->toDateTime().toString( Qt::ISODate ) );
+      }
+      else if ( type == QVariant::Date )
+      {
+        // binding a DATE value
+        query.addBindValue( it2->toDate().toString( Qt::ISODate ) );
+      }
+      else if ( type == QVariant::Time )
+      {
+        // binding a TIME value
+        query.addBindValue( it2->toTime().toString( Qt::ISODate ) );
+      }
       else
       {
         query.addBindValue( *it2 );