The QSql namespace contains miscellaneous identifiers used throughout the Qt SQL module. 更多...
头: | #include <QSql> |
qmake: | QT += sql |
enum | 定位 { BeforeFirstRow, AfterLastRow } |
enum | NumericalPrecisionPolicy { LowPrecisionInt32, LowPrecisionInt64, LowPrecisionDouble, HighPrecision } |
flags | ParamType |
enum | ParamTypeFlag { In, Out, InOut, Binary } |
enum | TableType { Tables, SystemTables, Views, AllTables } |
另请参阅 Qt SQL .
This enum type describes special SQL navigation locations:
常量 | 值 | 描述 |
---|---|---|
QSql::BeforeFirstRow
|
-1
|
Before the first record. |
QSql::AfterLastRow
|
-2
|
After the last record. |
另请参阅 QSqlQuery::at ().
Numerical values in a database can have precisions greater than their corresponding C++ types. This enum lists the policies for representing such values in the application.
常量 | 值 | 描述 |
---|---|---|
QSql::LowPrecisionInt32
|
0x01
|
Force 32bit integer values. In case of floating point numbers, the fractional part is silently discarded. |
QSql::LowPrecisionInt64
|
0x02
|
Force 64bit integer values. In case of floating point numbers, the fractional part is silently discarded. |
QSql::LowPrecisionDouble
|
0x04
|
Force
double
values. This is the default policy.
|
QSql::HighPrecision
|
0
|
Strings will be used to preserve precision. |
Note: The actual behaviour if an overflow occurs is driver specific. The Oracle database just returns an error in this case.
This enum is used to specify the type of a bind parameter.
常量 | 值 | 描述 |
---|---|---|
QSql::In
|
0x00000001
|
The bind parameter is used to put data into the database. |
QSql::Out
|
0x00000002
|
The bind parameter is used to receive data from the database. |
QSql::InOut
|
In | Out
|
The bind parameter is used to put data into the database; it will be overwritten with output data on executing a query. |
QSql::Binary
|
0x00000004
|
This must be OR'd with one of the other flags if you want to indicate that the data being transferred is raw binary data. |
The ParamType type is a typedef for QFlags <ParamTypeFlag>. It stores an OR combination of ParamTypeFlag values.
This enum type describes types of SQL tables.
常量 | 值 | 描述 |
---|---|---|
QSql::Tables
|
0x01
|
All the tables visible to the user. |
QSql::SystemTables
|
0x02
|
Internal tables used by the database. |
QSql::Views
|
0x04
|
All the views visible to the user. |
QSql::AllTables
|
0xff
|
All of the above. |