MySQL, 5th Edition

3. Data Types

Virtually everything you do in MySQL involves data in some way or another because, by definition, the purpose of a database management system is to manage data. Even a statement as simple as SELECT 1 involves evaluation of an expression to produce an integer data value.

Every data value in MySQL has a type. For example, 37.4 is a number and 'abc' is a string. Sometimes data types are explicit, such as when you issue a CREATE TABLE statement that specifies the type for each column you define as part of the table:

Click here to view code image

CREATE TABLE mytbl (   int_col  INT,       # integer-valued column   str_col  CHAR(20),  # string-valued column   date_col DATE       # date-valued column );

Other times data types are implicit, ...