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++.
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IBM DB2 data type
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SQL type description
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Recommended input (C++ or Qt data type)
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SMALLINT
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16-bit signed integer
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typedef qint16
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INTEGER
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32-bit signed integer
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typedef qint32
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BIGINT
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64-bit signed integer
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typedef qint64
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REAL
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32-bit Single-precision floating point
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typedef qreal
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DOUBLE PRECISION
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64-bit Double-precision floating point
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Mapped to
QString
for high precision doubles, otherwise qreal
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FLOAT
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64-bit Double-precision floating point
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typedef qreal
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CHAR
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Fixed-length, null-terminated character string
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Mapped to
QString
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VARCHAR
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Null-terminated varying length string
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Mapped to
QString
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LONG VARCHAR
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Not null-terminated varying length character string
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Mapped to
QString
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BLOB
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Not null-terminated varying binary string with 4-byte string length indicator
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Mapped to
QByteArray
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CLOB
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Character large string object
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Mapped to
QString
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DATE
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Null-terminated character string of the following format: yyyy-mm-dd
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Mapped to
QDate
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TIME
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Null-terminated character string of the following format: hh.mm.ss
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Mapped to
QTime
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TIMESTAMP
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Null-terminated character string of the following format: yyyy-mm-dd-hh.mm.ss.nnnnnn
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Mapped to
QDateTime
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Oracle Call Interface data type
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SQL type description
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Recommended input (C++ or Qt data type)
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NUMBER
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FLOAT, DOUBLE, PRECISIONc REAL
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Mapped to
QString
for high precision doubles, otherwise qreal
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NUMBER(38)
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INTEGER INT SMALLINT
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typedef qint8/16/32/64
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NUMBER(p,s)
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NUMERIC(p,s) DECIMAL(p,s)a
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By default mapping to
QString
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NVARCHAR2(n)
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Character string (NATIONAL CHARACTER VARYING(n) NATIONAL CHAR VARYING(n) NCHAR VARYING(n))
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Mapped to
QString
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NCHAR(n)
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Character string (NATIONAL CHARACTER(n) NATIONAL CHAR(n) NCHAR(n))
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Mapped to
QString
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CHAR(n)
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Character string (CHARACTER(n) CHAR(n))
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Mapped to
QString
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CLOB
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Character large string object
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Mapped to
QString
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BLOB
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A binary large object
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Mapped to
QByteArray
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TIMESTAMP
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Year, month, and day values of date, as well as hour, minute, and second values of time
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Mapped to
QDateTime
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PostgreSQL data type
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SQL type description
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Recommended input (C++ or Qt data type)
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BOOLEAN
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布尔
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bool
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SMALLINT
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16-bit signed integer
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typedef qint16
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INTEGER
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32-bit signed integer
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typedef qint32
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BIGINT
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64-bit signed integer
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typedef qint64
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REAL
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32-bit variable-precision floating point
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typedef qreal
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DOUBLE PRECISION
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64-bit variable-precision floating point
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Mapped to
QString
for high precision doubles, otherwise qreal
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DECIMAL VARIABLE
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user-specified precision, exact
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typedef qreal
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NUMERIC VARIABLE
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user-specified precision, exact
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typedef qreal
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VARCHAR
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variable-length character string
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Mapped to
QString
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CHARACTER
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Character string of fixed-length
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Mapped to
QString
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TEXT
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Character string of variable-length
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Mapped to
QString
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CLOB
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Character large string object
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Mapped to
QString
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TIMESTAMP
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8 bytes, both date and time
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Mapped to
QDateTime
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TIMESTAMP
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8 bytes, both date and time, with time zone
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Mapped to
QDateTime
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DATE
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4 bytes, dates only
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Mapped to
QDate
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TIME
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8 bytes, times of day only 00:00:00.00 - 23:59:59.99
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Mapped to
QTime
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TIME
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12 bytes times of day only, with time zone 00:00:00.00+12
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Mapped to
QDateTime
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Sybase Adaptive Server data type
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SQL type description
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Recommended input (C++ or Qt data type)
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BINARY
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Describes a fixed-length binary value up to 255 bytes in size.
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Mapped to
QByteArray
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CHAR
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Character String
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Mapped to
QString
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DATETIME
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Date and time. Range: 1753-01-01 00:00:00 through 9999-12-31 23:59:59.
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Mapped to
QDateTime
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NCHAR
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Character String of fixed length
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Mapped to
QString
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NVARACHAR
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Character String of variable length
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Mapped to
QString
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VARCHAR
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Character String of fixed length
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Mapped to
QString
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CLOB
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Character large string object
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Mapped to
QString
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TIMESTAMP
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A unique number within a database
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Mapped to
QString
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SMALLDATETIME
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Date and time. Range: 1900-01-01 00:00 through 2079-12-31 23:59
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Mapped to
QDateTime
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UNICHAR
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Character String of fixed length.(Unicode)
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Mapped to
QString
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UNIVARCHAR
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Character String of variable length.(Unicode)
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Mapped to
QString
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VARBINARY
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Describes a variable-length binary value up to 255 bytes in size
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Mapped to
QByteArray
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