diff --git a/lib/calcms/audio_recordings.pm b/lib/calcms/audio_recordings.pm
index a7b0195..ff93c96 100644
--- a/lib/calcms/audio_recordings.pm
+++ b/lib/calcms/audio_recordings.pm
@@ -21,9 +21,8 @@ sub debug;
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_audio_recordings' );
-    return { map { $_ => undef } @$cols };
+    my $dbh  = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_audio_recordings' );
 }
 
 # get playout entries
diff --git a/lib/calcms/db.pm b/lib/calcms/db.pm
index 97dfb99..00a0f47 100644
--- a/lib/calcms/db.pm
+++ b/lib/calcms/db.pm
@@ -115,8 +115,7 @@ sub get_columns($$) {
     my $table = shift;
 
     my $columns = db::get( $dbh, 'select column_name from information_schema.columns where table_name=?', [$table] );
-    my @result = map { $_->{column_name} } (@$columns);
-    return \@result;
+    return [ map { $_->{column_name} } @$columns ];
 }
 
 # get hash with table columns as keys
@@ -124,8 +123,8 @@ sub get_columns_hash($$) {
     my $dbh   = shift;
     my $table = shift;
 
-    my $columns = db::get_columns( $dbh, $table );
-    return { map { $_ => 1 } @$columns };
+    my $columns = db::get( $dbh, 'select column_name from information_schema.columns where table_name=?', [$table] );
+    return { map { $_->{column_name} => 1 } @$columns };
 }
 
 #returns last inserted id
diff --git a/lib/calcms/event_history.pm b/lib/calcms/event_history.pm
index 7f9c836..ac0ccbb 100644
--- a/lib/calcms/event_history.pm
+++ b/lib/calcms/event_history.pm
@@ -14,9 +14,8 @@ sub debug;
 sub get_columns ($){
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_event_history' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_event_history' );
 }
 
 sub get ($$){
diff --git a/lib/calcms/password_requests.pm b/lib/calcms/password_requests.pm
index 7d1ba89..3a4897d 100644
--- a/lib/calcms/password_requests.pm
+++ b/lib/calcms/password_requests.pm
@@ -22,8 +22,7 @@ sub get_columns ($) {
     my $config = shift;
 
     my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_password_requests' );
-    return { map { $_ => undef } @$cols };
+    return db::get_columns_hash( $dbh, 'calcms_password_requests' );
 }
 
 sub get ($$) {
diff --git a/lib/calcms/playout.pm b/lib/calcms/playout.pm
index 3645bea..aba9b83 100644
--- a/lib/calcms/playout.pm
+++ b/lib/calcms/playout.pm
@@ -18,9 +18,8 @@ sub debug;
 sub get_columns ($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_playout' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_playout' );
 }
 
 
diff --git a/lib/calcms/project.pm b/lib/calcms/project.pm
index 3e89d21..cba7be9 100644
--- a/lib/calcms/project.pm
+++ b/lib/calcms/project.pm
@@ -28,9 +28,8 @@ sub debug;
 sub get_columns ($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_projects' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_projects' );
 }
 
 # get projects
diff --git a/lib/calcms/series.pm b/lib/calcms/series.pm
index 6840810..c17e53a 100644
--- a/lib/calcms/series.pm
+++ b/lib/calcms/series.pm
@@ -32,9 +32,8 @@ sub debug;
 sub get_columns ($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_series' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_series' );
 }
 
 # get series content
diff --git a/lib/calcms/series_dates.pm b/lib/calcms/series_dates.pm
index 47087d7..15e5941 100644
--- a/lib/calcms/series_dates.pm
+++ b/lib/calcms/series_dates.pm
@@ -24,9 +24,8 @@ sub debug;
 sub get_columns ($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_series_dates' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_series_dates' );
 }
 
 # get all series_dates for studio_id and series_id within given time range
diff --git a/lib/calcms/series_schedule.pm b/lib/calcms/series_schedule.pm
index 53539f8..59ccc31 100644
--- a/lib/calcms/series_schedule.pm
+++ b/lib/calcms/series_schedule.pm
@@ -27,9 +27,7 @@ sub get_columns ($) {
     my $config = shift;
 
     my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_series_schedule' );
-    return { map { $_ => undef } @$cols };
-
+    return db::get_columns_hash( $dbh, 'calcms_series_schedule' );
 }
 
 #map schedule id to id
diff --git a/lib/calcms/studio_timeslot_dates.pm b/lib/calcms/studio_timeslot_dates.pm
index e14ff0b..0ed9ae9 100644
--- a/lib/calcms/studio_timeslot_dates.pm
+++ b/lib/calcms/studio_timeslot_dates.pm
@@ -20,9 +20,8 @@ sub debug;
 sub get_columns ($){
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_studio_timeslot_dates' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_studio_timeslot_dates' );
 }
 
 # get all studio_timeslot_dates for studio_id within given time range
diff --git a/lib/calcms/studio_timeslot_schedule.pm b/lib/calcms/studio_timeslot_schedule.pm
index 47c1340..649b107 100644
--- a/lib/calcms/studio_timeslot_schedule.pm
+++ b/lib/calcms/studio_timeslot_schedule.pm
@@ -18,9 +18,8 @@ sub debug;
 sub get_columns($) {
 	my $config = shift;
 
-	my $dbh     = db::connect($config);
-	my $cols    = db::get_columns( $dbh, 'calcms_studio_timeslot_schedule' );
-    return { map { $_ => undef } @$cols };
+	my $dbh = db::connect($config);
+	return db::get_columns_hash( $dbh, 'calcms_studio_timeslot_schedule' );
 }
 
 #map schedule id to id
diff --git a/lib/calcms/studios.pm b/lib/calcms/studios.pm
index 77f05ac..e5cc691 100644
--- a/lib/calcms/studios.pm
+++ b/lib/calcms/studios.pm
@@ -15,9 +15,8 @@ sub debug;
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_studios' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_studios' );
 }
 sub get($;$) {
     my $config = shift;
diff --git a/lib/calcms/user_default_studios.pm b/lib/calcms/user_default_studios.pm
index 58d0090..64816e4 100644
--- a/lib/calcms/user_default_studios.pm
+++ b/lib/calcms/user_default_studios.pm
@@ -8,8 +8,6 @@ use Data::Dumper;
 
 # table:   calcms_user_default_studios
 # columns: user, project_id, studio_id
-#use base 'Exporter';
-#our @EXPORT_OK = qw(get insert update delete get_columns);
 
 sub debug;
 
@@ -17,8 +15,7 @@ sub get_columns($) {
     my $config = shift;
 
     my $dbh  = db::connect($config);
-    my $cols = db::get_columns( $dbh, 'calcms_user_default_studios' );
-    return { map { $_ => undef } @$cols };
+    return db::get_columns_hash( $dbh, 'calcms_user_default_studios' );
 }
 
 sub get ($$) {
diff --git a/lib/calcms/user_sessions.pm b/lib/calcms/user_sessions.pm
index 97566f3..8ec069e 100644
--- a/lib/calcms/user_sessions.pm
+++ b/lib/calcms/user_sessions.pm
@@ -26,9 +26,8 @@ sub debug;
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_user_sessions' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_user_sessions' );
 }
 
 #map schedule id to id
diff --git a/lib/calcms/user_settings.pm b/lib/calcms/user_settings.pm
index 2a85de7..1e80718 100644
--- a/lib/calcms/user_settings.pm
+++ b/lib/calcms/user_settings.pm
@@ -136,9 +136,8 @@ sub getColorCss ($$) {
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_user_settings' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_user_settings' );
 }
 
 sub get ($$) {
diff --git a/lib/calcms/user_stats.pm b/lib/calcms/user_stats.pm
index 54aad9e..5320635 100644
--- a/lib/calcms/user_stats.pm
+++ b/lib/calcms/user_stats.pm
@@ -13,9 +13,8 @@ sub debug;
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_user_stats' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_user_stats' );
 }
 
 sub get ($$) {
diff --git a/lib/calcms/work_dates.pm b/lib/calcms/work_dates.pm
index c46ca2b..6a1cd4d 100644
--- a/lib/calcms/work_dates.pm
+++ b/lib/calcms/work_dates.pm
@@ -24,9 +24,8 @@ sub debug;
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_work_dates' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_work_dates' );
 }
 
 # get all work_dates for studio_id and schedule_id within given time range
diff --git a/lib/calcms/work_schedule.pm b/lib/calcms/work_schedule.pm
index 3aefb32..a543730 100644
--- a/lib/calcms/work_schedule.pm
+++ b/lib/calcms/work_schedule.pm
@@ -25,9 +25,8 @@ sub debug;
 sub get_columns($) {
     my $config = shift;
 
-    my $dbh     = db::connect($config);
-    my $cols    = db::get_columns( $dbh, 'calcms_work_schedule' );
-    return { map { $_ => undef } @$cols };
+    my $dbh = db::connect($config);
+    return db::get_columns_hash( $dbh, 'calcms_work_schedule' );
 }
 
 #map schedule id to id
diff --git a/website/agenda/planung/projects.cgi b/website/agenda/planung/projects.cgi
index 2978435..18794d0 100755
--- a/website/agenda/planung/projects.cgi
+++ b/website/agenda/planung/projects.cgi
@@ -86,7 +86,7 @@ sub delete_project {
 
     my $entry = {};
     for my $param ( keys %$params ) {
-        if ( defined $columns->{$param} ) {
+        if ( exists $columns->{$param} ) {
             $entry->{$param} = $params->{$param} || '';
         }
     }
@@ -113,7 +113,7 @@ sub save_project {
     my $columns = project::get_columns($config);
     my $entry   = {};
     for my $param ( keys %$params ) {
-        if ( defined $columns->{$param} ) {
+        if ( exists $columns->{$param} ) {
             $entry->{$param} = $params->{$param} || '';
         }
     }
diff --git a/website/agenda/planung/studios.cgi b/website/agenda/planung/studios.cgi
index e933fc2..18e26ed 100755
--- a/website/agenda/planung/studios.cgi
+++ b/website/agenda/planung/studios.cgi
@@ -82,7 +82,7 @@ sub delete_studio {
 
     my $entry = {};
     for my $param ( keys %$params ) {
-        if ( defined $columns->{$param} ) {
+        if ( exists $columns->{$param} ) {
             $entry->{$param} = $params->{$param} || '';
         }
     }
@@ -131,7 +131,7 @@ sub save_studio {
     my $columns = studios::get_columns($config);
     my $entry   = {};
     for my $param ( keys %$params ) {
-        if ( defined $columns->{$param} ) {
+        if ( exists $columns->{$param} ) {
             $entry->{$param} = $params->{$param} || '';
         }
     }