Add Run Statements In A Transaction as a MySQL TIL

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1371 TILs and counting..._
+_1372 TILs and counting..._
 
 ---
 
@@ -575,6 +575,7 @@ _1371 TILs and counting..._
 - [Dump A Database To A File](mysql/dump-a-database-to-a-file.md)
 - [Ignore Duplicates When Inserting Records](mysql/ignore-duplicates-when-inserting-records.md)
 - [List Databases And Tables](mysql/list-databases-and-tables.md)
+- [Run Statements In A Transaction](mysql/run-statements-in-a-transaction.md)
 - [Select Rows After An Offset](mysql/select-rows-after-an-offset.md)
 - [Show Create Statement For A Table](mysql/show-create-statement-for-a-table.md)
 - [Show Tables That Match A Pattern](mysql/show-tables-that-match-a-pattern.md)

mysql/run-statements-in-a-transaction.md

@@ -0,0 +1,27 @@
+# Run Statements In A Transaction
+
+I'm connecting to a production MySQL database to make some changes to a
+specific user account. That means I am going to run an `update` statement and I
+expect that statement to affect exactly *one* row in the `users` table.
+
+If I run the `update` statement in a transaction, then I can verify all looks
+good before committing those changes. And importantly, I can rollback the
+changes if anything looks off.
+
+```sql
+> start transaction;
+
+> update users set roles = 'admin' where id = '1234';
+Query ok, 1 row affected
+
+> select * from users where id = '1234';
+-- check that all looks good
+
+> commit;
+```
+
+In the above case, all looked good, so I ran `commit`. If more rows than I
+expected were affected or the changed record didn't look right, I could instead
+`rollback`. None of those changes would make it into live production data.
+
+[source](https://dev.mysql.com/doc/refman/8.0/en/commit.html)