Data Types for Qt-supported Database Systems

Recommended data types for database systems

Recommended Data Types for Qt-Supported Database Systems

This table shows the recommended data types for extracting data from the databases supported in Qt. Note that types used in Qt are not necessarily valid as input types to a specific database system. e.g., A double might work perfectly as input for floating point records in a particular database, but not necessarily as a storage format for output from that database, because it would be stored with 64-bit precision in C++.

IBM DB2 Data Types

IBM DB2 data type	SQL type description	Recommended input (C++ or Qt data type)
SMALLINT	16-bit signed integer	typedef qint16
INTEGER	32-bit signed integer	typedef qint32
BIGINT	64-bit signed integer	typedef qint64
REAL	32-bit Single-precision floating point	typedef qreal
DOUBLE PRECISION	64-bit Double-precision floating point	Mapped to QString for high precision doubles, otherwise qreal
FLOAT	64-bit Double-precision floating point	typedef qreal
CHAR	Fixed-length, null-terminated character string	Mapped to QString
VARCHAR	Null-terminated varying length string	Mapped to QString
LONG VARCHAR	Not null-terminated varying length character string	Mapped to QString
BLOB	Not null-terminated varying binary string with 4-byte string length indicator	Mapped to QByteArray
CLOB	Character large string object	Mapped to QString
DATE	Null-terminated character string of the following format: yyyy-mm-dd	Mapped to QDate
TIME	Null-terminated character string of the following format: hh.mm.ss	Mapped to QTime
TIMESTAMP	Null-terminated character string of the following format: yyyy-mm-dd-hh.mm.ss.nnnnnn	Mapped to QDateTime

Borland InterBase Data Types

Borland InterBase data type	SQL type description	Recommended input (C++ or Qt data type)
BOOLEAN	Boolean	bool
TINYINT	8 bit signed integer	typedef qint8
SMALLINT	16-bit signed integer	typedef qint16
INTEGER	32-bit signed integer	typedef qint32
BIGINT LONG	64-bit signed integer	typedef qint64
REAL FLOAT	32-bit floating point	typedef qreal
FLOAT	64-bit floating point	typedef qreal
DOUBLE	64-bit floating point	typedef qreal
DOUBLE PRECISION	64-bit Double-precision floating point	Mapped to QString for high precision doubles, otherwise qreal
VARCHAR STRING	Character string, Unicode	Mapped to QString
CLOB	Character large string object	Mapped to QString
DATE	Displays date. Format: ‘yyyy-mm-dd’	Mapped to QDate
TIME	Displays time. Format is ‘hh:mm:ss’ in 24-hour format	Mapped to QTime
TIMESTAMP	Displays a timestamp. Format is ‘yyyy-mm-dd hh:mm:ss’	Mapped to QDateTime

MySQL Data Types

MySQL data type	SQL type description	Recommended input (C++ or Qt data type)
TINYINT	8 bit signed integer	typedef qint8
TINYINT UNSIGNED	8 bit unsigned integer	typedef quint8
SMALLINT	16-bit signed integer	typedef qint16
SMALLINT UNSIGNED	16-bit unsigned integer	typedef quint16
INT	32-bit signed integer	typedef qint32
INT UNSIGNED	32-bit unsigned integer	typedef quint32
BIGINT	64-bit signed integer	typedef qint64
FLOAT	32-bit Floating Point	typedef qreal
DOUBLE	64-bit Floating Point	Mapped to QString for high precision doubles, otherwise qreal
CHAR	Character string	Mapped to QString
VARCHAR	Character string	Mapped to QString
TINYTEXT	Character string	Mapped to QString
TEXT	Character string	Mapped to QString
MEDIUMTEXT	Character string	Mapped to QString
LONGTEXT	Character string	Mapped to QString
CLOB	Character large string object	Mapped to QString
all BLOB types	BLOB	Mapped to QByteArray
DATE	Date without Time	Mapped to QDate
DATETIME	Date and Time	Mapped to QDateTime
TIMESTAMP	Date and Time	Mapped to QDateTime
TIME	Time	Mapped to QTime
YEAR	Year (int)	Mapped to QDateTime
ENUM	Enumeration of Value Set	Mapped to QString

Oracle Call Interface Data Types

Oracle Call Interface data type	SQL type description	Recommended input (C++ or Qt data type)
NUMBER	FLOAT, DOUBLE, PRECISIONc REAL	Mapped to QString for high precision doubles, otherwise qreal
NUMBER(38)	INTEGER INT SMALLINT	typedef qint8/16/32/64
NUMBER(p,s)	NUMERIC(p,s) DECIMAL(p,s)a	By default mapping to QString
NVARCHAR2(n)	Character string (NATIONAL CHARACTER VARYING(n) NATIONAL CHAR VARYING(n) NCHAR VARYING(n))	Mapped to QString
NCHAR(n)	Character string (NATIONAL CHARACTER(n) NATIONAL CHAR(n) NCHAR(n))	Mapped to QString
CHAR(n)	Character string (CHARACTER(n) CHAR(n))	Mapped to QString
CLOB	Character large string object	Mapped to QString
BLOB	A binary large object	Mapped to QByteArray
TIMESTAMP	Year, month, and day values of date, as well as hour, minute, and second values of time	Mapped to QDateTime

ODBC Data Types

ODBC data type	SQL type description	Recommended input (C++ or Qt data type)
BIT	Boolean	BOOL
TINYINT	8 bit integer	typedef qint8
SMALLINT	16-bit signed integer	typedef qint16
INTEGER	32-bit signed integer	typedef qint32
BIGINT	64-bit signed integer	typedef qint64
REAL	32-bit Single-precision floating point	typedef qreal
FLOAT	64-bit Double floating point	typedef qreal
DOUBLE	64-bit Double floating point	Mapped to QString for high precision doubles, otherwise qreal
CHAR	Character string	Mapped to QString
VARCHAR	Character string	Mapped to QString
LONGVARCHAR	Character string	Mapped to QString
CLOB	Character large string object	Mapped to QString
DATE	Character string	Mapped to QDate
TIME	Character Time, Character string	Mapped to QTime
TIMESTAMP	Character Time, Character string	Mapped to QDateTime

PostgreSQL Data Types

PostgreSQL data type	SQL type description	Recommended input (C++ or Qt data type)
BOOLEAN	Boolean	bool
SMALLINT	16-bit signed integer	typedef qint16
INTEGER	32-bit signed integer	typedef qint32
BIGINT	64-bit signed integer	typedef qint64
REAL	32-bit variable-precision floating point	typedef qreal
DOUBLE PRECISION	64-bit variable-precision floating point	Mapped to QString for high precision doubles, otherwise qreal
DECIMAL VARIABLE	user-specified precision, exact	typedef qreal
NUMERIC VARIABLE	user-specified precision, exact	typedef qreal
VARCHAR	variable-length character string	Mapped to QString
CHARACTER	Character string of fixed-length	Mapped to QString
TEXT	Character string of variable-length	Mapped to QString
CLOB	Character large string object	Mapped to QString
TIMESTAMP	8 bytes, both date and time	Mapped to QDateTime
TIMESTAMP	8 bytes, both date and time, with time zone	Mapped to QDateTime
DATE	4 bytes, dates only	Mapped to QDate
TIME	8 bytes, times of day only 00:00:00.00 - 23:59:59.99	Mapped to QTime
TIME	12 bytes times of day only, with time zone 00:00:00.00+12	Mapped to QDateTime

QSQLITE SQLite version 3 Data Types

QSQLITE SQLite version 3 data type	SQL type description	Recommended input (C++ or Qt data type)
NULL	NULL value.	NULL
INTEGER	Signed integer, stored in 8, 16, 24, 32, 48, or 64-bits depending on the magnitude of the value.	typedef qint8/16/32/64
REAL	64-bit floating point value.	typedef qreal
TEXT	Character string (UTF-8, UTF-16BE or UTF-16-LE).	Mapped to QString
CLOB	Character large string object	Mapped to QString
BLOB	The value is a BLOB of data, stored exactly as it was input.	Mapped to QByteArray

Sybase Adaptive Server Data Types

Sybase Adaptive Server data type	SQL type description	Recommended input (C++ or Qt data type)
BINARY	Describes a fixed-length binary value up to 255 bytes in size.	Mapped to QByteArray
CHAR	Character String	Mapped to QString
DATETIME	Date and time. Range: 1753-01-01 00:00:00 through 9999-12-31 23:59:59.	Mapped to QDateTime
NCHAR	Character String of fixed length	Mapped to QString
NVARACHAR	Character String of variable length	Mapped to QString
VARCHAR	Character String of fixed length	Mapped to QString
CLOB	Character large string object	Mapped to QString
TIMESTAMP	A unique number within a database	Mapped to QString
SMALLDATETIME	Date and time. Range: 1900-01-01 00:00 through 2079-12-31 23:59	Mapped to QDateTime
UNICHAR	Character String of fixed length.(Unicode)	Mapped to QString
UNIVARCHAR	Character String of variable length.(Unicode)	Mapped to QString
VARBINARY	Describes a variable-length binary value up to 255 bytes in size	Mapped to QByteArray

SQLite Version 2

SQLite version 2 is “typeless”. This means that you can store any kind of data you want in any column of any table, regardless of the declared data type of that column. We recommend that you map the data to QString .