條件查詢是可能有為空字段,拼接SQL語句時候要屏蔽掉這些字段.

package cn.pangpython.utils;

import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

/**
 * @author pangPython
 *  sql工具類
 */
public class SQLUtils {

    //根據請求參數動態生成sql，過濾空值
    //適用於條件查詢
    public static String DynamicSQL(Map<String,Object> map){

        String sql 
 
= " where ";

        //遍歷map把其中value為空的刪除
        Iterator it = map.entrySet().iterator();

        while(it.hasNext()){
            Map.Entry mapentry = (Entry) it.next();
            if(mapentry.getValue()!=null){
                sql = sql + mapentry.getKey() + " = " + mapentry.getValue()+" and ";
            }

        }

        
 
if(sql.trim().endsWith("and")){
            sql = sql.substring(0, sql.lastIndexOf("and"));
        }

        if(sql.equals(" where ")){
            return "";
        }

        //因為用到表的別名，需要替換
        sql = sql.replaceAll("user", "u");

        return sql;
    }
}

參考原文：https://blog.csdn.net/u012995856/article/details/52968684

Jfinal適用於條件查詢的動態SQL語句生成工具