net.sf.eodsql
Annotation Type Select

@Target(value=METHOD)
@Retention(value=RUNTIME)
public @interface Select

The @Select annotation is used to mark methods within a Query class that will return a DataSet. The Select annotation contains the SQL query that will be executed on the database, and whether the resulting DataSet will be a "connected" or "disconnected" DataSet to start with. Remember that a DataSet may be cleanly disconnected from the database.

Here is an example of how a @Select is used:

        public class User {
            public Integer id;
            public String username;
        }
        
        public interface UserQuery extends BaseQuery {
            @Select("SELECT * FROM user WHERE id = ?1")
            public DataSet<User> getUserById(int id);
        }
    

Any method annotated with @Select may return any one of the following datatypes:

• the exact class to map - this will either return the first result found, or null if no results where returned.
• the class wrapped in a DataSet - this is the preferred way of returning mulitple results, as it can remain connected to the database, or be disconnected at any time.
• an array of the class to bind to
• the class wrapped in a Set, List or Collection - these types have no connection to the database, the data is loaded into them and the result is returned.
Don't forget that DataSet inherits from List, and has all of it's read functionality.

Columns that cannot be mapped to fields are ignored, as are fields that cannot be mapped to columns. @Select SQL uses the exact same query parser as the Update annotation, and so can also accept complex types as it's parameters, and insert their fields into the SQL query.

Author:

jason

See Also:

Update

Optional Element Summary

boolean	disconnected Specify whether or not the DataSet resulting from a call to the annotated method will be connected to the database or not.
boolean	rubberstamp If rubberstamp is flagged as true, the annotated method must return a DataIterator, otherwise it will be rejected by the QueryTool.
String	sql The SQL query to execute on the database.
String	value The SQL query to execute on the database.

value

public abstract String value

The SQL query to execute on the database. The result set of the query will be mapped to the datatype specified in the method declaration.

See Also:

sql()

Default:

""

sql

public abstract String sql

The SQL query to execute on the database. The result set of the query will be mapped to the datatype specified in the method declaration. This value works in the exact same way as value(), but is used when you wish to specify values other than the SQL query.

Default:

""

disconnected

public abstract boolean disconnected

Specify whether or not the DataSet resulting from a call to the annotated method will be connected to the database or not.

See Also:

DataSet, DataSet.disconnect()

Default:

false

rubberstamp

public abstract boolean rubberstamp

If rubberstamp is flagged as true, the annotated method must return a DataIterator, otherwise it will be rejected by the QueryTool. Rubberstamping will cause the returned DataIterator to use a single instance of the data-object for all of the rows returned, instead of initializing a new one for each row. This can be used to save CPU time and memory, and is especially useful in display code.

Default:

false