com.blazebit.persistence.impl.dialect.MySQLDbmsLimitHandler Maven / Gradle / Ivy

/*
 * Copyright 2014 - 2020 Blazebit.
 *
 * Licensed 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 com.blazebit.persistence.impl.dialect;

import com.blazebit.persistence.impl.function.CyclicUnsignedCounter;

import java.sql.PreparedStatement;
import java.sql.SQLException;

/**
 * @author Christian Beikov
 * @since 1.2.0
 */
public class MySQLDbmsLimitHandler extends AbstractDbmsLimitHandler {

    private static final ThreadLocal threadLocalCounter = new ThreadLocal() {

        @Override
        protected CyclicUnsignedCounter initialValue() {
            return new CyclicUnsignedCounter(-1);
        }

    };

    public MySQLDbmsLimitHandler() {
        super(20);
    }

    public MySQLDbmsLimitHandler(int length) {
        super(length);
    }

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

    @Override
    public void applySql(StringBuilder sqlSb, boolean isSubquery, String limit, String offset) {
        if (limit != null) {
            if (offset != null) {
                sqlSb.append(" limit ").append(offset).append(',').append(limit);
            } else {
                sqlSb.append(" limit ").append(limit);
            }
        } else if (offset != null) {
            // The biggest possible limit to be able to make an OFFSET only query
            sqlSb.append(" limit ").append(offset).append(",18446744073709551610");
        }
    }

    @Override
    public int bindLimitParametersAtEndOfQuery(Integer limit, Integer offset, PreparedStatement statement, int index) throws SQLException {
        if (limit != null) {
            if (offset != null) {
                statement.setInt(index, offset);
                statement.setInt(index + 1, limit);
                return 2;
            } else {
                statement.setInt(index, limit);
                return 1;
            }
        } else if (offset != null) {
            statement.setInt(index, offset);
            return 1;
        }

        return 0;
    }

}