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Sybase dbQueue Reference Guide

Appendix A: Datatypes

Appendix A

dbQueue Datatypes

dbQueue messages use datatypes that correspond to SQL datetypes defined by ODBC.

Table A-1 lists the dbQueue datatypes. The "Additional Attributes" column lists required information for defining the datatype. Settings for other attributes are ignored.

Table A-1: dbQueue datatypes

dbQueue Datatype	Description	Additional Attributes
DBQ_BINARY	Fixed length binary	length (1-255)
DBQ_BIT	Bit data
DBQ_CHAR	Fixed length string	length (1-255)
DBQ_DATETIME	Timestamp
DBQ_DECIMAL	Decimal number	precision (1-38), scale (0 -18, < precision)
DBQ_FLOAT	Double precision floating point
DBQ_IMAGE	Long binary data	length (1 - 2,097,152)
DBQ_INT	Signed integer
DBQ_MONEY	Currency
DBQ_NUMERIC	Decimal number	precision (1-38), scale (0 -18, < precision)
DBQ_REAL	Single precision floating point
DBQ_SMALLDATETIME	Timestamp
DBQ_SMALLINT	Small signed integer
DBQ_SMALLMONEY	Small currency value
DBQ_TEXT	Long character data	length (1 - 2,097,152)
DBQ_TINYINT	Tiny signed integer
DBQ_VARBINARY	Variable length binary	length (1 - 255)
DBQ_VARCHAR	Variable length string	length (1 - 255)

Datatypes in Packaged Queues

dbQueue automatically sets the definitions and ranges of datatypes for packaged queues. Sybase Adaptive Server has identical datatype definitions.

• Strings
• Numeric
• Money
• Date and Time
• Bit Data
• Text and Binary

Strings

The dbQueue objects library provides the following string datatypes:

• DBQ_CHAR - A string value capable of representing any character in the character set chosen by the client application. The maximum length is 255 bytes. Values are not blank-padded.
• DBQ_VARCHAR - Same as DBQ_CHAR.

Numeric

The dbQueue objects library supplies the following numeric types:

• DBQ_DECIMAL - A decimal number with precision and scale. Precision may be from 1 to 38 digits. The default value for precision is 18 digits. Scale may be from 0 to 37 digits. The default value for scale is 0.
• DBQ_FLOAT - A signed floating point number with 15 digits of precision and capable of representing numbers within the range 1.798e+308 to 2.225e-308.
• DBQ_INT - An integer representing whole numbers from -2³¹ to 2³¹ - 1 inclusive.
• DBQ_NUMERIC - Identical to DBQ_DECIMAL.
• DBQ_REAL - A signed floating point number with 6 digits of precision representing numbers within the range 3.403e+38 to 1.175e-38.
• DBQ_SMALLINT - An integer representing whole numbers from -2¹⁵ to 2¹⁵ - 1 inclusive.
• DBQ_TINYINT - An integer representing whole numbers from 0 to 255 inclusive.

Money

dbQueue supplies these money datatypes:

• DBQ_SMALLMONEY - A currency value between +214,748.3647 and -214,748.3648.
• DBQ_MONEY - A currency value between +922,337,203,685,477.5807 and -922,337,203,685,477.5808.

Date and Time

dbQueue supplies these datatypes for representing datetime values:

• DBQ_SMALLDATETIME - A datetime value representing dates from January 1, 1900 to June 6, 2079.
• DBQ_DATETIME - A datetime value representing dates from January 1, 1753 to December 31, 9999.

Bit Data

dbQueue supplies this datatype for representing bit data:

• DBQ_BIT - A datatype capable of holding 0 or 1.

Text and Binary

dbQueue supplies these datatypes for representing text and binary data:

• DBQ_VARBINARY - A binary field. The maximum length is 255 bytes.
• DBQ_TEXT - A character field. The maximum length of a DBQ_TEXT field in a message is 2,097,152 bytes.
• DBQ_IMAGE - An image field containing binary data. The maximum length of a DBQ_IMAGE field in a message is 2,097,152 bytes.

  Note: dbQueue guarantees messages containing data within the ranges listed can enqueue and dequeue without loss of information. In some cases, dbQueue may also accept values outside the published ranges. However, you should be aware that in these cases, dbQueue cannot guarantee the data will be uncorrupted when dequeued.

Mapping dbQueue Datatypes to DBMS Datatypes

dbQueue automatically maps its own datatypes to equivalent DBMS datatypes for visibe queues. The definition and range depends on the underlying datasource.

Because messages must fit in a single row, messages stored in a database must fit within the page size.

Table A-2 lists datatype mapping between dbQueue, Adaptive Server, SQL Anywhere, and ODBC.

Table A-2: Datatype mapping between standards

dbQueue dataype name	Adaptive Server datatype name	SQL Anywhere datatype name	ODBC datatype name
DBQ_BINARY	binary(n)	binary(n)	SQL_BINARY
DBQ_BIT	bit	bit	SQL_BIT
DBQ_CHAR	char	char	SQL_CHAR
DBQ_DATETIME	datetime	datetime	SQL_TIMESTAMP
DBQ_DECIMAL	decimal(p,s)	decimal(p,s)	SQL_DECIMAL
DBQ_FLOAT	float(15)	float	SQL_DOUBLE
DBQ_IMAGE	image(n)	image(n)	SQL_LONGVARBINARY
DBQ_INTEGER	int	int	SQL_INTEGER
DBQ_MONEY	money	money	SQL_DECIMAL
DBQ_NUMERIC	numeric(p,s)	numeric(p,s)	SQL_NUMERIC
DBQ_REAL	real	real	SQL_REAL
DBQ_SMALLDATETIME	smalldatetime	datetime	SQL_TIMESTAMP
DBQ_SMALLINT	smallint	smallint	SQL_SMALLINT
DBQ_SMALLMONEY	smallmoney	smallmoney	SQL_DECIMAL
DBQ_TEXT	text	text	SQL_LONGVARCHAR
DBQ_TINYINT	tinyint	tinyint	SQL_TINYINT
DBQ_VARBINARY	varbinary(n)	varbinary(n)	SQL_VARBINARY
DBQ_VARCHAR	varchar(n)	varchar(n)	SQL_VARCHAR

In Adaptive Server, DBQ_TEXT and DBQ_IMAGE map to integer references. The image and text data are stored in separate tables.

Unlike Adaptive Server, dbQueue automatically assigns precision to DBQ_FLOAT.

Null Values

dbQueue currently does not support null values for any datatype.

dbQueue Types for C++ and ActiveX

dbQueue datatype mapping to C++ is described in Chapter 1, "Using the dbQueue Objects Library."

dbQueue datatype mapping to ActiveX is described in Chapter 3, "Using the ActiveX Interface."