From 5efe8b6da41fe373fdf5917bb0dc0cdfba0e9f64 Mon Sep 17 00:00:00 2001
From: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Date: Tue, 24 Mar 2020 16:22:33 +0100
Subject: [PATCH] Bug 18177: Do not remove columns if at least one value exists

---
 installer/data/mysql/atomicupdate/bug_18177.perl | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/installer/data/mysql/atomicupdate/bug_18177.perl b/installer/data/mysql/atomicupdate/bug_18177.perl
index 0426fda963..61b0e5e543 100644
--- a/installer/data/mysql/atomicupdate/bug_18177.perl
+++ b/installer/data/mysql/atomicupdate/bug_18177.perl
@@ -3,10 +3,19 @@ if( CheckVersion( $DBversion ) ) {
 
     for my $column ( qw(othersupplier booksellerfax booksellerurl bookselleremail currency) ) {
         if( column_exists( 'aqbooksellers', $column ) ) {
-            $dbh->do(qq|
-                ALTER TABLE aqbooksellers
-                DROP COLUMN $column
+            my ($count) = $dbh->selectrow_array(qq|
+                SELECT COUNT(*)
+                FROM aqbooksellers
+                WHERE $column IS NOT NULL AND $column <> ""
             |);
+            if ( $count ) {
+                warn "Warning - Cannot remove column aqbooksellers.$column. At least one value exists";
+            } else {
+                $dbh->do(qq|
+                    ALTER TABLE aqbooksellers
+                    DROP COLUMN $column
+                |);
+            }
         }
     }
 
-- 
2.20.1