Dark Horse day11 dirty read data & amp; solution, dark horse day11

Dark Horse day11 dirty Data Reading & Solutions, dark horse day11

Database:

Create table account (
Id int primary key auto_increment,
Name varchar (20 ),
Money double
);

Insert into account values (null, 'a, 100 );

Insert into account values (null, 'B', 100 );

1. Demonstrate dirty reading

Open two client windows. The level of client A is the default Repeatable read of the database-this can prevent dirty read/non-repeated read problems, but cannot prevent virtual read (phantom read) problems. Changing the level of client B to the Read uncommitted level with the highest efficiency cannot solve the dirty Read problem.

Window:

Start transaction: start transaction;

Account a transfers RMB 10 to account B: update account set money = money-10 where name = 'a ';

Add 10 RMB to account B: update account set money = money + 10 where name = 'B ';

Do not submit transactions;

Window B:

Start transaction: start transaction;

Query account B data in the database: select * from account;

Window:

Rollback transaction: rollback;

Window B:

Query data: select * from account;

Dirty read data is generated.

Solution:

Change the isolation level of window B to Read committed.

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