• mybatisPlus条件构造器常用方法


    首先是.select

    在MP查询中,默认查询所有的字段,如果有需要也可以通过select方法进行指定字段。其中要注意的细节:

    1. wrapper.select("pname")
    2. .eq("pname","张三")
    3. .or().eq("price",300);
    4. List userList = userDao.selectList(wrapper);

    使用select进行sql语句拼接时,不会识别在实体类中属性对应的操作:

    SELECT pname FROM USER WHERE (pname = ? or price =? )

    当数据库表中的字段名,与实体类对象的属性名不一致时

    1. wrapper.select("pname as name")
    2. .eq("pname","张三")
    3. .or().eq("price",300);
    4. List userList = userDao.selectList(wrapper);

    这样拼接出来的sql语句:

    SELECT pname as name FROM user WHERE (pname = ? OR price = ? )

    其他条件 

    函数名说明例子
    eq等于 =例:eq(“name”,“张三”) :name = ‘张三’
    ne不等于<>例: eq(“name”,“老王”)  —>  name <> ‘老王’
    gt大于>例:gt(“age”,18)  —>  age > 18
    ge大于等于>=例:ge(“age”,18)  —>  age >= 18
    lt小于<例:lt(“age”,18)  —>  age < 18
    le小于<=例:le(“age”,18)  —>  age <= 18
    betweenBETWEEN值1 AND值2例:between(“age”,18,30)  —>  age between 18 and 30
    notBetweenNOT BETWEEN值1 AND值2例: notBetween(“age”,18,30)  —>  age not between 18 and 30
    likeLIKE ‘%值%’例: like(“name”,“王”)  —–>  name like '%王%’
    notLikeNOT LIKE ‘%值%’例: notLike (“name”,“王”)  —>  name not like '%王%’
    likeLeftLIKE '%值’例:likeLeft (“name”,“王”)  —–>  name like '%王’
    likeRightLIKE’值%’例: likeRight(“name”,“王”)  —>  name like ‘王%’
    isNull字段IS NULL例: isNul1 (“name”)  —>  name is null
    isNotNull字段IS NOT NULL例: isNotNull(“name”)  —>  name is not null
    in字段IN (v0, v1,…)例: in(“age”,{1,2,3} )  —–>  age in (1,2,3)
    notIn字段NOT IN (v0, v1,…)例: notIn(“age”,1,2,3)  —>  age not in (1,2,3)
    inSql字段IN ( sql语句)inSql(“id”, “select id from table where id < 3”)   —–>  id in (select id from table where id < 3)
    notInSql字段NOT IN ( sql语句)notInSql(“id”, “select id from table where id < 3”)   —–>  age not in (select id from table where id < 3)
    groupBy分组:GROUP BY 字段,…例: groupBy(“id”, “name”)  —>  group by id, name
    orderByAsc排序:ORDER BY字段,… ASC例: orderByAsc(“id”, “name”)  —>  order by id ASC, name ASC
    orderByDesc排序:ORDER BY 字段,…DESC例: orderByDesc(“id”, “name”)  —>  order by id DESC, name DESC
    orderBy排序:ORDER BY字段,…例: orderBy(true,true,“id”,“name”)  —–>  order by id ASC,name ASC
    havingHAVING ( sql语句)having(“sum(age) >{0}”,11)  —>  having sum(age) > 11
    or拼接OR主动调用or表示紧接着下一个方法不是用and连接!(不调用or则默认为使用and连接)例:eq(“id”,1).or().eq(“name”,“老王”)  —>  id = 1 or name = '老王
    andAND嵌套例: and(i -> i.eq(“name”,“李白”).ne(“status”,“活着”))  —>  and (name ='李白’ and status ’活着’)
    apply拼接sql该方法可用于数据库函数动态入参的params对应前面sqlHaving内部的{index}部分.这样是不会有sql注入风险的,反之会有! 例: apply(“date_format(dateColumn, ‘%Y一%m-%d’) ={0}”, “2008-08-08”)  —>  date_format(dateColumn,’%Y一%m-%d’) = ‘2008-08-08’")
    last无视优化规则直接拼接到sql 的最后无视优化规则直接拼接到sql 的最后只能调用一次,多次调用以最后一次为准有sql注入的风险,请谨慎使用例: last(“limit 1”)
    exists拼接EXISTS ( sql语句)—>   exists (select id from table where age = 1)例: notExists(“select id from table where age = 1”) —>exists (select id from table where age = 1)
    notExists拼接NOT EXISTS ( sql语句)例: notExists(“select id from table where age = 1”)  —–>  not exists (select id from table where age = 1)
    nested正常嵌套不带AND或者 OR正常嵌套不带AND或者OR例: nested(i -> i.eq(“name”,“李白”).ne(“status”,“活着”))  —>  (name = '李白’and status 活着’)

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  • 原文地址:https://blog.csdn.net/w13966597931/article/details/127412114