Skip to main content

Table Properties


MySQL manages tables using storage engines, each of which handles tables that have a given set of characteristics. Different storage engines have differing performance characteristics, and can be chosen based on which engine most closely matches the char acteristics that are needed. For example, a table may require transactional capabilities and guaranteed data in tegrity even if a crash occurs, or it may require a very fast lookup table stored in memory for which the contents can be lost in a crash and reloaded at the next server startup.  With MySQL, these choices can be made on a per-table basis. Any given table is managed by a particular storage engine.

Options can be added to the CREATE TABLE  command in order to control the manner in which the entire table is handled.


ENGINE={MyISAM | InnoDB | MEMORY}
  •   Indicates the storage engine to be used for the table
  •  MyISAM is the default storage engine (unless --default-storage-engine has been set)

COMMENT='<comment>'  

  •  Up to 60 characters of free form text  

CHARACTER SET=<character set> 

  • Specifies the character set for the table 
  •   Precede with DEFAULT to assign the default character set
  • Can be shortened to CHARSET  

COLLATE= <collation_name>
  • Specifies the collation for the table
  •  Precede with DEFAULT  to assign the default collation
Labels:

Comments

Post a Comment

Popular posts from this blog

PHP INTRODUCTION

                     PHP  (recursive acronym for  PHP: Hypertext Preprocessor ) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. PHP stands for  P HP:  H ypertext  P reprocessor PHP is a server-side scripting language, like ASP PHP scripts are executed on the server PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.) PHP is an open source software PHP is free to download and use Why PHP? PHP runs on different platforms (Windows, Linux, Unix, etc.) PHP is compatible with almost all servers used today (Apache, IIS, etc.) PHP is FREE to download from the official PHP resource:  www.php.net PHP is easy to learn and runs efficiently on the server side What can PHP do? Anything. PHP is mainly focused on server-side scripting, so you can...
6 comments
Read more

Storage Engine Breakdown

The following diagram represents a simplified view of the MySQL server and its interaction with the  storage engines. The following properties are storage engine dependant: • Storage Medium – Each table uses its own method of storing the data it contains. • Transactional Capabilities – Certain storage engines handle transactional processing which ensures that integrity of a database is maintained during the processing of multiple SQL statements.
Post a Comment
Read more

Outer Joins

Whereas an INNER JOIN will find combinations of matching rows from joined tables, the OUTER JOIN also finds the instances where a row in one table has no match in another table. An OUTER JOIN find matches (just like an INNER JOIN), but also identifies mismatches. Two forms of outer joins are LEFT JOIN and RIGHT JOIN . These do not use the comma separator or the INNER JOIN keywords. They each answer the same kinds of questions, but differ slightly in their syntax. That is a LEFT JOIN can always be re-written into a equivalent RIGHT JOIN. (In the following sections, the terms left table and right table refer to the tables named first and second in the FROM clause, respectively.)  Left Outer Join A left join is a type of outer join, written using the LEFT JOIN keywords. A left join treats the left table (the first one named) as a reference table and produces output for each row selected from it, whether or not the row is matched by rows in the right table. Like a join w...
Post a Comment
Read more