Added Readme

This commit is contained in:
Maksymilian Lúmenn Stachowiak 2023-12-11 23:58:57 +01:00
parent 137f21f3d0
commit c2ed485d65
1 changed files with 58 additions and 0 deletions

58
README.MD Normal file
View File

@ -0,0 +1,58 @@
# Purpose
This repostiory contains examples which might be used to show/explain why and when deadlocks happen in MSSQL.
# How to
1. Open two different SQL sessions.
2. In each session open one file.
3. Run SQL commands according to comments.
For example - running Read Commited should look like:
### Session 1
```sql
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
BEGIN TRANSACTION
UPDATE Wycieczki
SET cena = cena*2
WHERE
kraj = 'Bangkok'
-- STEP 1 RUN ABOVE
```
### Session 2
```sql
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
BEGIN TRANSACTION
UPDATE Bilety
SET cena = cena * 2
WHERE
kraj = 'Ateny'
-- STEP 2 - RUN ABOVE
```
### Session 1
```sql
SELECT
*
FROM
Bilety
WHERE
kraj = 'Ateny'
-- STEP 3 RUN BETWEEN 1 AND 3
COMMIT TRANSACTION -- COMMIT AFTER DEADLOCK HAPPENS
```
### Session 2
```sql
SELECT
*
FROM
Wycieczki
WHERE
kraj = 'Bangkok'
-- STEP 4 RUN BETWEEN 2 AND 4
COMMIT TRANSACTION -- COMMIT AFTER DEADLOCK HAPPENS
```