org.apache.marmotta.kiwi.persistence.mysql.MySQLDialect.java Source code

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Here is the source code for org.apache.marmotta.kiwi.persistence.mysql.MySQLDialect.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.marmotta.kiwi.persistence.mysql;

import org.apache.commons.lang3.StringUtils;
import org.apache.marmotta.kiwi.exception.DriverNotFoundException;
import org.apache.marmotta.kiwi.persistence.KiWiDialect;

/**
 * A dialect for MySQL. When using MySQL, make sure the JDBC connection URL has the following arguments (workarounds
 * for non-standard MySQL behaviour):
 * <ul>
 *     <li>characterEncoding=utf8</li>
 *     <li>zeroDateTimeBehavior=convertToNull</li>
 * </ul>
 * Otherwise MySQL will not behave correctly. For example use a connection URL like:
 * <code>
 * jdbc:mysql://localhost:3306/kiwitest?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull
 * </code>
    
 * <p/>
 * Author: Sebastian Schaffert
 */
public class MySQLDialect extends KiWiDialect {

    public MySQLDialect() throws DriverNotFoundException {
        try {
            Class.forName(getDriverClass());
        } catch (ClassNotFoundException e) {
            throw new DriverNotFoundException(getDriverClass());
        }
    }

    /**
     * Return the name of the driver class (used for properly initialising JDBC connections)
     *
     * @return
     */
    @Override
    public String getDriverClass() {
        return "com.mysql.jdbc.Driver";
    }

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

    @Override
    public String getRegexp(String text, String pattern, String flags) {
        if (StringUtils.containsIgnoreCase(flags, "i")) {
            return String.format("lower(%s) RLIKE lower(%s)", text, pattern);
        } else {
            return text + " RLIKE " + pattern;
        }
    }

    /**
     * Return true in case the SPARQL RE flags contained in the given string are supported.
     *
     * @param flags
     * @return
     */
    @Override
    public boolean isRegexpSupported(String flags) {
        if (StringUtils.containsIgnoreCase(flags, "s")) {
            return false;
        }
        if (StringUtils.containsIgnoreCase(flags, "m")) {
            return false;
        }
        if (StringUtils.containsIgnoreCase(flags, "x")) {
            return false;
        }

        return true;
    }

    @Override
    public String getILike(String text, String pattern) {
        return "lower(" + text + ") LIKE lower(" + pattern + ")";
    }

    /**
     * Return the name of the aggregate function for group concatenation (string_agg in postgres, GROUP_CONCAT in MySQL)
     *
     * @param value
     * @param separator
     * @return
     */
    @Override
    public String getGroupConcat(String value, String separator, boolean distinct) {
        if (distinct) {
            value = "DISTINCT " + value;
        }
        if (separator != null) {
            return String.format("GROUP_CONCAT(%s SEPARATOR %s)", value, separator);
        } else {
            return String.format("GROUP_CONCAT(%s)", value);
        }
    }

    /**
     * Return the SQL timezone value for a KiWiDateLiteral, corrected by the timezone offset. In PostgreSQL, this is
     * e.g. computed by (ALIAS.tvalue + ALIAS.tzoffset * INTERVAL '1 second')
     *
     * @param alias
     * @return
     */
    @Override
    public String getDateTimeTZ(String alias) {
        return String.format("DATE_ADD(%s.tvalue, INTERVAL %s.tzoffset SECOND)", alias, alias);
    }

    /**
     * Get the query string that can be used for validating that a JDBC connection to this database is still valid.
     * Typically, this should be an inexpensive operation like "SELECT 1",
     *
     * @return
     */
    @Override
    public String getValidationQuery() {
        return "SELECT 1";
    }

}