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 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
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 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
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 */
package org.hibernate.dialect;

import java.sql.Types;

import org.hibernate.dialect.function.NoArgSQLFunction;
import org.hibernate.dialect.function.VarArgsSQLFunction;
import org.hibernate.type.StandardBasicTypes;

A SQL dialect for Ingres 9.3 and later versions.

Changes:

Support for the SQL functions current_time, current_timestamp and current_date added
Type mapping of Types.TIMESTAMP changed from "timestamp with time zone" to "timestamp(9) with time zone"
Improved handling of "SELECT...FOR UPDATE" statements
Added support for pooled sequences
Added support for SELECT queries with limit and offset
Added getIdentitySelectString
Modified concatination operator

Author:
Enrico Schenk, Raymond Fan/**
 * A SQL dialect for Ingres 9.3 and later versions.
 * <p/>
 * Changes:
 * <ul>
 * <li>Support for the SQL functions current_time, current_timestamp and current_date added</li>
 * <li>Type mapping of <code>Types.TIMESTAMP</code> changed from "timestamp with time zone" to "timestamp(9) with time zone"</li>
 * <li>Improved handling of "SELECT...FOR UPDATE" statements</li>
 * <li>Added support for pooled sequences</li>
 * <li>Added support for SELECT queries with limit and offset</li>
 * <li>Added getIdentitySelectString</li>
 * <li>Modified concatination operator</li>
 * </ul>
 *
 * @author Enrico Schenk
 * @author Raymond Fan
 */
public class Ingres9Dialect extends IngresDialect {
	
Constructs a Ingres9Dialect
/**
	 * Constructs a Ingres9Dialect
	 */
	public Ingres9Dialect() {
		super();
		registerDateTimeFunctions();
		registerDateTimeColumnTypes();
		registerFunction( "concat", new VarArgsSQLFunction( StandardBasicTypes.STRING, "(", "||", ")" ) );
	}

	
Register functions current_time, current_timestamp, current_date
/**
	 * Register functions current_time, current_timestamp, current_date
	 */
	protected void registerDateTimeFunctions() {
		registerFunction( "current_time", new NoArgSQLFunction( "current_time", StandardBasicTypes.TIME, false ) );
		registerFunction(
				"current_timestamp", new NoArgSQLFunction(
				"current_timestamp",
				StandardBasicTypes.TIMESTAMP,
				false
		)
		);
		registerFunction( "current_date", new NoArgSQLFunction( "current_date", StandardBasicTypes.DATE, false ) );
	}

	
Register column types date, time, timestamp
/**
	 * Register column types date, time, timestamp
	 */
	protected void registerDateTimeColumnTypes() {
		registerColumnType( Types.DATE, "ansidate" );
		registerColumnType( Types.TIMESTAMP, "timestamp(9) with time zone" );
	}

	// lock acquisition support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	@Override
	public boolean supportsOuterJoinForUpdate() {
		return false;
	}

	@Override
	public boolean forUpdateOfColumns() {
		return true;
	}

	// SEQUENCE support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	@Override
	public String getIdentitySelectString() {
		return "select last_identity()";
	}

	@Override
	public String getQuerySequencesString() {
		return "select seq_name from iisequences";
	}

	@Override
	public boolean supportsPooledSequences() {
		return true;
	}

	// current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	@Override
	public boolean isCurrentTimestampSelectStringCallable() {
		return false;
	}

	@Override
	public boolean supportsCurrentTimestampSelection() {
		return true;
	}

	@Override
	public String getCurrentTimestampSelectString() {
		return "select current_timestamp";
	}

	@Override
	public String getCurrentTimestampSQLFunctionName() {
		return "current_timestamp";
	}

	// union subclass support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	@Override
	public boolean supportsUnionAll() {
		return true;
	}

	// Informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	@Override
	public boolean doesReadCommittedCauseWritersToBlockReaders() {
		return true;
	}

	@Override
	public boolean doesRepeatableReadCauseReadersToBlockWriters() {
		return true;
	}

	// limit/offset support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	@Override
	public boolean supportsLimitOffset() {
		return true;
	}

	@Override
	public boolean supportsVariableLimit() {
		return false;
	}

	@Override
	public boolean useMaxForLimit() {
		return false;
	}

	@Override
	public String getLimitString(String querySelect, int offset, int limit) {
		final StringBuilder soff = new StringBuilder( " offset " + offset );
		final StringBuilder slim = new StringBuilder( " fetch first " + limit + " rows only" );
		final StringBuilder sb = new StringBuilder( querySelect.length() + soff.length() + slim.length() )
				.append( querySelect );
		if ( offset > 0 ) {
			sb.append( soff );
		}
		if ( limit > 0 ) {
			sb.append( slim );
		}
		return sb.toString();
	}
}