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//$Id: IngresDialect.java 10963 2006-12-08 16:06:14Z [email protected] $
package org.hibernate.dialect;

import java.sql.Types;

import org.hibernate.Hibernate;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.NoArgSQLFunction;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.dialect.function.VarArgsSQLFunction;


/**
 * An Ingres SQL dialect.
 * 
 * Known limitations:
 * - only supports simple constants or columns on the left side of an IN, making (1,2,3) in (...) or (FOR UPDATE OF, allowing
	 * particular rows to be locked?
	 *
	 * @return True (Ingres does support "for update of" syntax...)
	 */
	public boolean supportsForUpdateOf() {
		return true;
	}

	/**
	 * The syntax used to add a column to a table (optional).
	 */
	public String getAddColumnString() {
		return "add column";
	}

	/**
	 * The keyword used to specify a nullable column.
	 *
	 * @return String
	 */
	public String getNullColumnString() {
		return " with null";
	}

	/**
	 * Does this dialect support sequences?
	 *
	 * @return boolean
	 */
	public boolean supportsSequences() {
		return true;
	}

	/**
	 * The syntax that fetches the next value of a sequence, if sequences are supported.
	 *
	 * @param sequenceName the name of the sequence
	 *
	 * @return String
	 */
	public String getSequenceNextValString(String sequenceName) {
		return "select nextval for " + sequenceName;
	}

	public String getSelectSequenceNextValString(String sequenceName) {
		return sequenceName + ".nextval";
	}

	/**
	 * The syntax used to create a sequence, if sequences are supported.
	 *
	 * @param sequenceName the name of the sequence
	 *
	 * @return String
	 */
	public String getCreateSequenceString(String sequenceName) {
		return "create sequence " + sequenceName;
	}

	/**
	 * The syntax used to drop a sequence, if sequences are supported.
	 *
	 * @param sequenceName the name of the sequence
	 *
	 * @return String
	 */
	public String getDropSequenceString(String sequenceName) {
		return "drop sequence " + sequenceName + " restrict";
	}

	/**
	 * A query used to find all sequences
	 */
	public String getQuerySequencesString() {
		return "select seq_name from iisequence";
	}

	/**
	 * The name of the SQL function that transforms a string to
	 * lowercase
	 *
	 * @return String
	 */
	public String getLowercaseFunction() {
		return "lowercase";
	}

	/**
	 * Does this Dialect have some kind of LIMIT syntax?
	 */
	public boolean supportsLimit() {
		return true;
	}

	/**
	 * Does this dialect support an offset?
	 */
	public boolean supportsLimitOffset() {
		return false;
	}

	/**
	 * Add a LIMIT clause to the given SQL SELECT
	 *
	 * @return the modified SQL
	 */
	public String getLimitString(String querySelect, int offset, int limit) {
		if ( offset > 0 ) {
			throw new UnsupportedOperationException( "offset not supported" );
		}
		return new StringBuffer( querySelect.length() + 16 )
				.append( querySelect )
				.insert( 6, " first " + limit )
				.toString();
	}

	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 true;
	}

	/**
	 * Ingres explicitly needs "unique not null", because "with null" is default
	 */
	public boolean supportsNotNullUnique() {
		return false;
	}

	/**
	 * Does this dialect support temporary tables?
	 */
	public boolean supportsTemporaryTables() {
		return true;
	}

	public String getCreateTemporaryTableString() {
		return "declare global temporary table";
	}

	public String getCreateTemporaryTablePostfix() {
		return "on commit preserve rows with norecovery";
	}

	public String generateTemporaryTableName(String baseTableName) {
		return "session." + super.generateTemporaryTableName( baseTableName );
	}


	/**
	 * Expression for current_timestamp
	 */
	public String getCurrentTimestampSQLFunctionName() {
		return "date(now)";
	}

	// Overridden informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	public boolean supportsSubselectAsInPredicateLHS() {
		return false;
	}

	public boolean supportsEmptyInList() {
		return false;
	}

	public boolean supportsExpectedLobUsagePattern () {
		return false;
	}
}