Merge pull request #108 from microsoft/DeleteAll

DeleteAll #107

content/BCBestPractices/Performance/DeleteAll/index.md

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+title = "DeleteAll"
+weight = 1180
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+
+<_Created by waldo, Described by waldo_\>
+
+## Description
+
+When you perform a "DeleteAll" when there is nothing to delete, it will still perform a lock.  When you for example perform a DeleteAll on an empty table, it will result in a table lock.
+Therefore it's good practice to always check if the table is empty when performing a DeleteAll.
+
+## Bad code
+
+```al
+    EmptyTableWLD.SetRange(Code, 'AJ');
+    EmptyTableWLD.DeleteAll(true);
+```
+
+## Good code
+
+```al
+    EmptyTableWLD.SetRange(Code, 'AJ');
+    if not EmptyTableWLD.IsEmpty() then
+        EmptyTableWLD.DeleteAll(true);
+```
+
+## Discussions
+
+You can discuss the guideline [here](https://github.com/microsoft/alguidelines/discussions/107)
+
+You can find discussions on all "Best Practices" [here](https://github.com/microsoft/alguidelines/discussions/categories/bc-best-practices).
+
+If you don't find the discussion of this guideline, please feel free to create a new one with the same title as this article.