Database integration for Qt applications.
This overview assumes that you have at least a basic knowledge of SQL. You should be able to understand simple
SELECT,INSERT,UPDATE，和DELETEstatements. Although theQSqlTableModelclass provides an interface to database browsing and editing that does not require a knowledge of SQL, a basic understanding of SQL is highly recommended. A standard text covering SQL databases is An Introduction to Database Systems (7th Ed.) by C. J. Date, ISBN 0201385902.
这些类提供对 SQL 数据库的访问。
qsql.html
The QSql namespace contains miscellaneous identifiers used throughout the Qt SQL module.
The QSqlDriverCreatorBase class is the base class for SQL driver factories.
QSqlDriverCreatorThe QSqlDriverCreator class is a template class that provides a SQL driver factory for a specific driver type.
The QSqlDatabase class handles a connection to a database.
The QSqlDriver class is an abstract base class for accessing specific SQL databases.
The QSqlError class provides SQL database error information.
QSqlField 类操纵 SQL 数据库表和视图中的字段。
The QSqlIndex class provides functions to manipulate and describe database indexes.
QSqlQuery 类提供执行和操纵 SQL 语句的手段。
QSqlRecord 类封装数据库记录。
The QSqlResult class provides an abstract interface for accessing data from specific SQL databases.
The QSqlQueryModel class provides a read-only data model for SQL result sets.
The QSqlRelationalTableModel class provides an editable data model for a single database table, with foreign key support.
The QSqlTableModel class provides an editable data model for a single database table.
SQL 类分为 3 层：
This comprises the classes
QSqlDriver,QSqlDriverCreator,QSqlDriverCreatorBase,QSqlDriverPlugin，和QSqlResult.This layer provides the low-level bridge between the specific databases and the SQL API layer. See SQL 数据库驱动程序 了解更多信息。
These classes provide access to databases. Connections are made using the
QSqlDatabaseclass. Database interaction is achieved by using theQSqlQueryclass. In addition toQSqlDatabaseandQSqlQuery, the SQL API layer is supported byQSqlError,QSqlField,QSqlIndex，和QSqlRecord.
These classes link the data from a database to data-aware widgets. They include
QSqlQueryModel,QSqlTableModel，和QSqlRelationalTableModel. These classes are designed to work with Qt’s 模型/视图框架 .注意：
QCoreApplicationobject must be instantiated before using any of these classes.
