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mybatis QueryWrapper的條件構(gòu)造之a(chǎn)pply、last、select解析

更新時間：2022年03月22日 11:58:58 作者：Neic

這篇文章主要介紹了mybatis QueryWrapper的條件構(gòu)造之a(chǎn)pply、last、select，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

QueryWrapper條件構(gòu)造之a(chǎn)pply、last、select

場景：查詢數(shù)據(jù)庫限制條數(shù)時

mysql上的limit使用

QueryWrapper needSyn = new QueryWrapper();
needSyn.ge("ModifyDate",lmtSynRec.getLatestDate());
needSyn.last("limit 200");
List<CusCarInfo> needData = cusCarInfoMapper.selectList(needSyn);

如果是oracle則可以用apply

needSyn.apply("rownum < {0}" , 200);

如果是sqlserver

建議自己寫sql查詢語句

<select id="getSynList" resultType="com.xmeport.project.model.entity.CusCarInfo">
? ? select top ${top} ?* ?from CUS_CAR_INFO t where t.ModifyDate > cast(#{latestDate} as datetime) orderBy?
?t.ModifyDate asc
</select>
List<CusCarInfo> getSynList(int top, Date latestDate);

或者使用QueryWrapper的select

QueryWrapper<CusCarInfo> wrapper ?= new QueryWrapper();
wrapper.select("top 200 *");
return this.list(wrapper);

以上就是根據(jù)最新時間查詢top條數(shù)據(jù)

傳入的字段是時間類型，就用#{} 占位符接收。如果是具體的一個數(shù)字或字符可以用 ${ }來接收。

條件構(gòu)造器QueryWrapper實例

我們再搞幾個實例來深入理解下條件構(gòu)造器QueryWrapper的用法：

案例一

查詢姓李的，并且出生日期范圍是1993-02-09到1994-04-09的員工

sql實現(xiàn)：

SELECT * FROM t_employee WHERE DATE_FORMAT(birthday,'%Y-%m-%d')>='1993-02-09' AND DATE_FORMAT(birthday,'%Y-%m-%d')<='1994-04-09' AND NAME LIKE '李%'

mp實現(xiàn)：

/**
?* 查詢姓李的，并且出生日期范圍是1993-02-09到1994-04-09的員工
?* sql：SELECT * FROM t_employee WHERE DATE_FORMAT(birthday,'%Y-%m-%d')>='1993-02-09' AND DATE_FORMAT(birthday,'%Y-%m-%d')<='1994-04-09' AND NAME LIKE '李%'
?*/
@Test
public void selectByQueryWrapper3(){
? QueryWrapper<Employee> queryWrapper=new QueryWrapper();
? // QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
? queryWrapper.apply("DATE_FORMAT(birthday,'%Y-%m-%d')>={0} and DATE_FORMAT(birthday,'%Y-%m-%d')<={1}","1993-02-09","1994-04-09").likeRight("name","李");
? List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
? System.out.println(employeeList);
}

案例二

查詢姓李的或者郵箱不為空并且是女性的員工

sql實現(xiàn)：

SELECT * FROM t_employee WHERE NAME LIKE '李%' OR (email IS NOT NULL AND gender ='女')

mp實現(xiàn)：

/**
?* 查詢姓李的或者郵箱不為空并且是女性的員工
?* sql：SELECT * FROM t_employee WHERE NAME LIKE '李%' OR (email IS NOT NULL AND gender ='女')
?*/
@Test
public void selectByQueryWrapper4(){
? QueryWrapper<Employee> queryWrapper=new QueryWrapper();
? // QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
? queryWrapper.likeRight("name","李").or(wq->wq.isNotNull("email").eq("gender","女"));
? List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
? System.out.println(employeeList);
}

案例三

查詢姓李的并且郵箱不為空或者是女性的員工

sql實現(xiàn)：

SELECT * FROM t_employee WHERE NAME LIKE '李%' AND (email IS NOT NULL OR gender ='女')

mp實現(xiàn)：

/**
?* 查詢姓李的并且郵箱不為空或者是女性的員工
?* sql：SELECT * FROM t_employee WHERE NAME LIKE '李%' AND (email IS NOT NULL OR gender ='女')
?*/
@Test
public void selectByQueryWrapper5(){
? QueryWrapper<Employee> queryWrapper=new QueryWrapper();
? // QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
? queryWrapper.likeRight("name","李").and(wq->wq.isNotNull("email").or().eq("gender","女"));
? List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
? System.out.println(employeeList);
}

案例四

查詢屬于編號1,2,3部門的并且薪水小于等于3500的員工根據(jù)年齡從大到小排序顯示

sql實現(xiàn)：

SELECT * FROM t_employee WHERE salary<=3500 AND departmentId IN (1,2,3) ORDER BY birthday ASC

mp實現(xiàn)：

/**
?* 查詢屬于編號1,2,3部門的并且薪水小于等于3500的員工 根據(jù)年齡從大到小排序顯示
?* sql：SELECT * FROM t_employee WHERE salary<=3500 AND departmentId IN (1,2,3) ORDER BY birthday ASC
?*/
@Test
public void selectByQueryWrapper6(){
? QueryWrapper<Employee> queryWrapper=new QueryWrapper();
? // QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
? queryWrapper.likeRight("name","李").and(wq->wq.isNotNull("email").or().eq("gender","女"));
? List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
? System.out.println(employeeList);
}

以上為個人經(jīng)驗，希望能給大家一個參考，也希望大家多多支持腳本之家。

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