Data Types
Each
column in a table has a particular data type associated with it.
SQL-92 defines a fairly broad set of data types. Different RDBMS
packages provide extensions to these basic types, for multimedia
data, Java objects, and so on. Oracle’s
NUMBER
data type, for instance, allows database
designers to specify the exact precision of integer and
floating-point data types. The basic SQL-92 types are listed in Figure 12-1. The names in parentheses are SQL-92 specified
alternates for the main type names.
Table 12-1. SQL-92 Data Types
SQL Data Type |
Description |
---|---|
INTEGER (INT) |
A signed integer value. The number of bits represented is implementation-dependent. |
SMALLINT |
A smaller signed integer value, used when storage or memory is at a premium. Generally 8 bits but implementation-dependent. |
NUMERIC |
A signed fixed-precision decimal. When creating a
|
DECIMAL |
Defined the same way as a |
REAL |
A single-precision floating-point value. Range and accuracy are implementation-dependent. |
DOUBLE PRECISION (DOUBLE) |
A double-precision floating-point value. Range and accuracy are
implementation dependent, but are equal to or better than a
|
BIT |
A fixed number (one or more) of bits. A length specifier
( |
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