MySQL Transaction & Character Set

MysqlTransactions

Innodb the transaction in the storage engine is fully serviced ACID:

1. atomicity, 2. consistency,3. isolation, 4. Persistence

the understanding is similar to Oracle .

Transaction ISOLATION Level

1. READ UNCOMMITTED not submitted;

2. Read Committed reading has been submitted;

3. Repeatable Read is repeatable, similar to Oracle 's flash back query using undo;

4. Serializable serial read, seldom used.

Changes to the isolation level:

1. through the set command;

2. start the default isolation level for the database by modifying the configuration file -mysqld

MysqlCharacter Set

The Mysql character set includes the character set (character) and proofing Rules (collation).

The character set defines how MySQL data strings are stored, and the proofing rules define how strings are compared.

selection of character sets

1. handle a wide variety of Chinese characters, in different countries, should be selected Unicode, for MySQL is UTF-8, each character three bytes;

2. only support Chinese, large data volume, high performance requirements, optional GBK, two bytes of each kanji;

3. handle Mobile Internet business,utf8mb4 character set;

on-line business, which is usually UTF-8 Character Set .

to view supported character sets

Mysql can support different character sets, and different fields of the same machine, library, or table can specify different character sets.

Mysql–uroot–proot123–e "Show CharacterSet"

meaning of character set parameters

Character_set_client: Client Character Set

Character_set_connection: Connection Character Set

Character_set_database: Database character Set, configuration file designation or build table designation

Character_set_results: Returns the result character set

Character_set_server: Server character Set, configuration file designation, or database build table specified

This article is from the "90SirDB" blog, be sure to keep this source http://90sirdb.blog.51cto.com/8713279/1792887

MySQL Transaction & Character Set