Data Types

DB Access Module for MySQL User's Guide
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2.3 Data Types

The classes RWDBColumn and RWDBValue have an associated RWDBValue::ValueType that specifies the data type of the database column or field being referenced. Mapping between this data type and the database vendor type runs in both directions:

When fetching data or retrieving information about tables, the DB Access Module for MySQL converts the MySQL type value into RWDBValue::ValueTypes. This mapping is shown in Table 1, which also gives the C++ data type corresponding to the RWDBValue::ValueType.
When creating tables, the DB Access Module for MySQL maps the given RWDBValue::ValueType into a MySQL type code. This mapping is shown in Table 2.

The RWDBValue::ValueType, accessible through the type() method, are uniform across all Access Modules. For a complete explanation of the DB Interface Module data model, see Chapter 7, "The Data Model," in the DB Interface Module User's Guide, and RWDBValue in the SourcePro C++ API Reference Guide.

Table 1: Type mapping when retrieving data

MySQL Data Type	RWDBValue::ValueType	C++ Data Type
`decimal numeric`	`Decimal`	*RWDecimalPortable*
`bigint`	`UnsignedLongLong, LongLong`	`unsigned long long, long long`
`tinyblob, blob, mediumblob, longblob`	`Blob`	*RWDBBlob*
`double`	`Double`	`double`
`float`	`Float`	`float`
`tinyint`	`Char, UnsignedChar`	`char, unsigned char`
`smallint`	`Short, UnsignedShort`	`short, unsigned short`
`integer, mediumint`	`Long, UnsignedLong`	`long, unsigned long`
`char, varchar, tinytext, mediumtext, text, longtext, enum, set`	`String`	*RWCString*
`date`	`Date`	*RWDate*
`datetime, time, timestamp`	`DateTime`	*RWDBDateTime¹, RWDateTime*
`year`	`UnsignedShort`	`unsigned short`

RWDBDateTime is deprecated. Please use RWDateTime.

Table 2: Type mapping when creating tables

RWDBValue::ValueType	MySQL Data Types
`Blob`	`MEDIUMBLOB` if length is `RWDB_NO_TRAIT`. If 0<= length <= 255 `TINYBLOB`. If 256 <= length <=65,535 `BLOB`. If 65,536 <= length <= 16,777,215 `MEDIUMBLOB.` Otherwise, `LONGBLOB`.
`Tiny, UnsignedTiny, Char, UnsignedChar`	`TINYINT`
`Date`	`DATE`
`DateTime`	`DATETIME`
`Decimal (p,s)`	`DECIMAL` using precision and scale of column. If p <= 0 defaults to 8. If s <= 0 defaults to 0.
`Double`	`DOUBLE`
`Float (P)`	`FLOAT` if precision is `RWDB_NO_TRAIT`. Otherwise, `FLOAT (p)` using precision of column.
`Int`, `UnsignedInt, Long`, `UnsignedLong`	`INT`
`Short`, `UnsignedShort`	`SMALLINT`
`LongLong, UnsignedLongLong`	`BIGINT`
`String`	`MEDIUMTEXT` if length is `RWDB_NO_TRAIT`. If 0<= length <= 255 `VARCHAR(length)` using the `storageLength` of the *RWDBColumn*. If 256 <= length <= 65,535 `TEXT`. If 65,536 <= length <= 16,777,215 `MEDIUMTEXT.` Otherwise `LONGTEXT.`

2.3.1 Restrictions on the Use of Data Types

Table 3 outlines the known restrictions associated with each DB Interface Module value type.

Table 3: Restrictions on the use of DB Interface Module data types

RWDBValue::ValueType	Restrictions
`Blob`	No restrictions.
`Char, UnsignedChar`	No restrictions.
`Blob`	No restrictions
`Char, UnsignedChar`	No restrictions
`Date`	No restrictions.
`DateTime`	No restrictions.
`Decimal`	No restrictions.
`Double`	No restrictions.
`Duration`	This data type is not supported.
`Float`	No restrictions.
`Int, UnsignedInt`	No restrictions.
`Long, UnsignedLong`	No restrictions.
`LongLong, UnsignedLongLong`	No restrictions.
`MBString`	This data type is not supported.
`LongDouble`	No restrictions.
`String`	No restrictions.
`Short, UnsignedShort`	No restrictions.
`WString`	This data type is not supported.
`UString`	This data type is not supported.

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