The SELECT Statement
The SelectExp class represents the SELECT statement.
The SELECT statement is the SQL statement for retrieving information, with a few restrictions and extensions specific to WQL. Although the SQL SELECT statement is typically used in the database environment to retrieve particular columns from tables, the WQL SELECT statement is used to retrieve instances of a single class. WQL does not support queries across multiple classes.
The SELECT expression identifies the search list. The SELECT statement can take one of the following forms:
|
SELECT Statement |
Selects |
|---|---|
|
SELECT * |
All instances of the specified class and any of its subclasses. |
|
SELECT attr_exp, attr_exp...attr_exp |
Only instances of the specified class and any of its subclasses that contain the specifies identifiers. |
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