org.postgresql.core.Query Maven / Gradle / Ivy
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/*-------------------------------------------------------------------------
*
* Copyright (c) 2004-2014, PostgreSQL Global Development Group
* Copyright (c) 2004, Open Cloud Limited.
*
*
*-------------------------------------------------------------------------
*/
package org.postgresql.core;
/**
* Abstraction of a generic Query, hiding the details of
* any protocol-version-specific data needed to execute
* the query efficiently.
*
* Query objects should be explicitly closed when no longer
* needed; if resources are allocated on the server for this
* query, their cleanup is triggered by closing the Query.
*
* @author Oliver Jowett ([email protected])
*/
public interface Query {
/**
* Create a ParameterList suitable for storing parameters
* associated with this Query.
*
* If this query has no parameters, a ParameterList will
* be returned, but it may be a shared immutable object.
* If this query does have parameters, the returned
* ParameterList is a new list, unshared by other callers.
*
* @return a suitable ParameterList instance for this query
*/
ParameterList createParameterList();
/**
* Stringize this query to a human-readable form, substituting
* particular parameter values for parameter placeholders.
*
* @param parameters a ParameterList returned by this Query's
* {@link #createParameterList} method, or null to
* leave the parameter placeholders unsubstituted.
* @return a human-readable representation of this query
*/
String toString(ParameterList parameters);
/**
* Close this query and free any server-side resources associated
* with it. The resources may not be immediately deallocated, but
* closing a Query may make the deallocation more prompt.
*
* A closed Query should not be executed.
*/
void close();
boolean isStatementDescribed();
boolean isEmpty();
}