avoid running migration twice, fixes #1265

Closes #1265

Merge request studip/studip!774

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/migrations/DatabaseMigrationTrait.php b/lib/migrations/DatabaseMigrationTrait.php
new file mode 100644
index 0000000..f8fad72
--- /dev/null
+++ b/lib/migrations/DatabaseMigrationTrait.php
@@ -0,0 +1,22 @@
+<?php
+trait DatabaseMigrationTrait
+{
+    /**
+     * Returns whether a key/index with the given name exists on the given
+     * table.
+     */
+    protected function keyExists(string $table, string $key): bool
+    {
+        $query = "SHOW INDEX FROM `$table` WHERE Key_name = ?";
+        return (bool) DBManager::get()->fetchOne($query, [$key]);
+    }
+
+    /**
+     * Returns whether a column with the given name exists on the given table.
+     */
+    protected function columnExists(string $table, string $column): bool
+    {
+        $query = "SHOW COLUMNS FROM `{$table}` LIKE ?";
+        return (bool) DBManager::get()->fetchOne($query, [$column]);
+    }
+}