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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
 * distributed under license by Red Hat Inc.
 *
 * 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
 * Boston, MA  02110-1301  USA
 */
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 * @author Raymond Fan */ public class Ingres9Dialect extends IngresDialect { public Ingres9Dialect() { super(); registerDateTimeFunctions(); registerDateTimeColumnTypes(); registerFunction( "concat", new VarArgsSQLFunction( StandardBasicTypes.STRING, "(", "||", ")" ) ); } /** * 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 */ protected void registerDateTimeColumnTypes() { registerColumnType(Types.DATE, "ansidate"); registerColumnType(Types.TIMESTAMP, "timestamp(9) with time zone"); } // lock acquisition support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /** * Does this dialect support FOR UPDATE in conjunction with outer * joined rows? * * @return True if outer joined rows can be locked via FOR UPDATE. */ public boolean supportsOuterJoinForUpdate() { return false; } /** * Is FOR UPDATE OF syntax supported? * * @return True if the database supports FOR UPDATE OF syntax; * false otherwise. */ public boolean forUpdateOfColumns() { return true; } // SEQUENCE support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /** * Get the select command used to retrieve the last generated sequence * value. * * @return Statement to retrieve last generated sequence value */ public String getIdentitySelectString() { return "select last_identity()"; } /** * Get the select command used retrieve the names of all sequences. * * @return The select command; or null if sequences are not supported. * @see org.hibernate.tool.hbm2ddl.SchemaUpdate */ public String getQuerySequencesString() { return "select seq_name from iisequences"; } /** * Does this dialect support "pooled" sequences. Not aware of a better name * for this. Essentially can we specify the initial and increment values? * * @return True if such "pooled" sequences are supported; false otherwise. * @see #getCreateSequenceStrings(String, int, int) * @see #getCreateSequenceString(String, int, int) */ public boolean supportsPooledSequences() { return true; } // current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /** * Should the value returned by {@link #getCurrentTimestampSelectString} be * treated as callable. Typically this indicates that JDBC escape sytnax is * being used... * * @return True if the {@link #getCurrentTimestampSelectString} return is * callable; false otherwise. */ public boolean isCurrentTimestampSelectStringCallable() { return false; } /** * Does this dialect support a way to retrieve the database's current * timestamp value? * * @return True if the current timestamp can be retrieved; false otherwise. */ public boolean supportsCurrentTimestampSelection() { return true; } /** * Retrieve the command used to retrieve the current timestammp from the * database. * * @return The command. */ public String getCurrentTimestampSelectString() { return "select current_timestamp"; } /** * Expression for current_timestamp */ public String getCurrentTimestampSQLFunctionName() { return "current_timestamp"; } // union subclass support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /** * Does this dialect support UNION ALL, which is generally a faster variant * of UNION? * * @return True if UNION ALL is supported; false otherwise. */ public boolean supportsUnionAll() { return true; } // Informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /** * For the underlying database, is READ_COMMITTED isolation implemented by * forcing readers to wait for write locks to be released? * * @return true */ public boolean doesReadCommittedCauseWritersToBlockReaders() { return true; } /** * For the underlying database, is REPEATABLE_READ isolation implemented by * forcing writers to wait for read locks to be released? * * @return true */ public boolean doesRepeatableReadCauseReadersToBlockWriters() { return true; } // limit/offset support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /** * Does this dialect's LIMIT support (if any) additionally support * specifying an offset? * * @return true */ public boolean supportsLimitOffset() { return true; } /** * Does this dialect support bind variables (i.e., prepared statememnt * parameters) for its limit/offset? * * @return false */ public boolean supportsVariableLimit() { return false; } /** * Does the LIMIT clause take a "maximum" row number instead * of a total number of returned rows? */ public boolean useMaxForLimit() { return false; } /** * Add a LIMIT clause to the given SQL SELECT * * @return the modified SQL */ public String getLimitString(String querySelect, int offset, int limit) { StringBuilder soff = new StringBuilder(" offset " + offset); StringBuilder slim = new StringBuilder(" fetch first " + limit + " rows only"); 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(); } }




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