com.jn.sqlhelper.dialect.internal.CacheDialect Maven / Gradle / Ivy

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/*
 * Copyright 2019 the original author or authors.
 *
 * Licensed under the LGPL, Version 3.0 (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.gnu.org/licenses/lgpl-3.0.html
 *
 * 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.jn.sqlhelper.dialect.internal;

import com.jn.sqlhelper.dialect.internal.limit.LimitHelper;
import com.jn.sqlhelper.dialect.internal.limit.TopLimitHandler;
import com.jn.sqlhelper.dialect.pagination.RowSelection;

import java.sql.CallableStatement;
import java.sql.SQLException;


public class CacheDialect extends AbstractDialect {
    public CacheDialect() {
        super();
        setLimitHandler(new TopLimitHandler() {
            public String processSql(String sql,boolean isSubquery, boolean useLimitVariable, RowSelection rowSelection) {
                if (rowSelection.hasOffset()) {
                    throw new UnsupportedOperationException("query result offset is not supported");
                }

                int insertionPoint = sql.startsWith("select distinct") ? 15 : 6;
                String substring="";
                if(useLimitVariable && isUseLimitInVariableMode(isSubquery)){
                    substring = " TOP ? ";
                }else {
                    int lastRow = getMaxOrLimit(rowSelection);
                    substring = " TOP " + lastRow ;
                }
                return new StringBuilder(sql.length() + 8).append(sql).insert(insertionPoint, substring).toString();
            }
        });
    }

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

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

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

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

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

    @Override
    public int registerResultSetOutParameter(CallableStatement statement, int col)
            throws SQLException {
        return col;
    }
}