fix QgsPostgresProvider::maximumValue()

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@11904 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: jef

src/providers/postgres/qgspostgresprovider.cpp

@@ -1869,13 +1869,13 @@ QVariant QgsPostgresProvider::maximumValue( int index )
     if ( sqlWhereClause.isEmpty() )
     {
       sql = QString( "select max(%1) from %2" )
-            .arg( fieldExpression( fld ) )
+            .arg( quotedIdentifier( fld.name() ) )
             .arg( mSchemaTableName );
     }
     else
     {
       sql = QString( "select max(%1) from %2 where %3" )
-            .arg( fieldExpression( fld ) )
+            .arg( quotedIdentifier( fld.name() ) )
             .arg( mSchemaTableName )
             .arg( sqlWhereClause );
     }