cqengine

本文主要是介绍cqengine，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

1.参考：

https://www.cnblogs.com/tankaixiong/p/12920667.html

2.语法

SQL

public static void main(String[] args) {
    SQLParser<Car> parser = SQLParser.forPojoWithAttributes(Car.class, createAttributes(Car.class));
    IndexedCollection<Car> cars = new ConcurrentIndexedCollection<Car>();
    cars.addAll(CarFactory.createCollectionOfCars(10));
 
    ResultSet<Car> results = parser.retrieve(cars, "SELECT * FROM cars WHERE (" +
                                    "(manufacturer = 'Ford' OR manufacturer = 'Honda') " +
                                    "AND price <= 5000.0 " +
                                    "AND color NOT IN ('GREEN', 'WHITE')) " +
                                    "ORDER BY manufacturer DESC, price ASC");
    for (Car car : results) {
        System.out.println(car); // Prints: Honda Accord, Ford Fusion, Ford Focus
    }
}

3.like

%xxx%：查询username字段中包含xxx的记录。

select * from user where username like '%xxx%'; 

%xxx：查询username字段中以xxx结尾的记录。

select * from user where username like '%xxx';

xxx%：查询username字段中以xxx开头的记录。

select * from user where username like 'xxx%';

4.https://blog.csdn.net/ldc5306590/article/details/53705319?utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromMachineLearnPai2%7Edefault-1.control&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromMachineLearnPai2%7Edefault-1.control

String sqlString="select * from tb_wf_main where trim(WF_NAME) = '   " + wfName.trim() + "  '    ";

5.

package com.huawi;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


/**
 * WHERE (( name LIKE '%1%' OR name LIKE '%2%' ) AND age  >= 20 ) ORDER BY manufacturer DESC, price ASC
 */
public class AAA {


    public static void main(String[] args) {
        String head = "WHERE (";
        String end = " ) ORDER BY manufacturer DESC, price ASC";

        // list
        ArrayList<String> sqlLists = new ArrayList<>();
        List<String> strings = Arrays.asList("1", "25");
        String listCenter = parseListSql(strings);
        sqlLists.add(listCenter);


        // 数值
        StringBuffer stringBuffer1 = new StringBuffer();
        String ageCenter = stringBuffer1.append(" AND age ").append(" >= ").append(20).toString();
        sqlLists.add(ageCenter);


        // 字符
        StringBuffer stringBuffer2 = new StringBuffer();
        String StringCenter = stringBuffer2.append(" AND addr ").append(" = ").append("'" + "anhui" + "'").toString();
        sqlLists.add(StringCenter);

        StringBuffer stringBufferFinal = new StringBuffer();
        for (String s :
                sqlLists) {
            stringBufferFinal.append(s);
        }
        String finalString = head + stringBufferFinal.toString() + end;
        System.out.println(finalString);
    }

    public static String parseListSql(List<String> strings) {
        StringBuffer stringBuffer = new StringBuffer();
        for (String s : strings) {
            stringBuffer.append("name").append(" LIKE ").append("'" + '%' + ',' + s + ',' + '%' + "'").append(" OR ");
        }
        String center = stringBuffer.append(")").toString();
        center = center.substring(0, center.length() - 5);
        center = "( " + center + " )";
        return center;
    }


}

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