added transaction

AnuragAnalog · AnuragAnalog · commit c921d74fc84a · 2019-11-30T05:22:07.000+05:30
diff --git a/README.md b/README.md
@@ -228,7 +228,7 @@ select avg(population) from city group by population;
 
 #### Count function
 ```sql
-select count(name) from city group by name;
+select district, count(district) from city group by district;
 ```
 
 #### Maximum function
@@ -262,4 +262,35 @@ show databases;
 #### Calling procedure
 ```sql
 call display_dbs();
-```
+```
+
+## Transaction
+
+#### Begin transaction
+```sql
+start transaction;
+```
+
+#### Create savepoint
+```sql
+savepoint sv_pt;
+```
+
+```sql
+delete from city;       -- changing data in table
+```
+
+#### Rollback
+```sql
+rollback to sv_pt;
+```
+
+#### Releasing savepoint
+```sql
+release savepoint sv_pt;
+```
+
+#### Commiting changes
+```sql
+commit;
+```
diff --git a/transaction.sql b/transaction.sql
@@ -0,0 +1,40 @@
+
+-- creating basic stuff to work on them
+create database cheatsheet;
+use cheatsheet;
+
+create table city 
+(
+    id int primary key,
+    name varchar(17),
+    countrycode varchar(3),
+    district varchar(20),
+    population int
+);
+
+insert into city values (6, "Rotterdam", "NLD", "Zuid-Holland", 593321);
+insert into city values (3878, "Scottsdale", "USA", "Arizona", 202705);
+insert into city values (3965, "Corona", "USA", "California", 124966);
+insert into city values (3973, "Concord", "USA", "California", 121780);
+insert into city values (3977, "Cedar Rapids", "USA", "Iowa", 120758);
+insert into city values (3982, "Coral Springs", "USA", "Florida", 117549);
+insert into city values (4054, "Fairfield", "USA", "California", 92256);
+insert into city values (4058, "Boulder", "USA", "Colorado", 91238);
+insert into city values (4061, "Fall River", "USA", "Massachusetts", 90555);
+
+-- begin transaction
+start transaction;
+
+-- create savepoint
+savepoint sv_pt;
+
+delete from city;       -- changing data in table
+
+-- rollback
+rollback to sv_pt;
+
+-- releasing savepoint
+release savepoint sv_pt;
+
+-- commiting changes
+commit;
