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:
wrapper.select("pname") .eq("pname","张三") .or().eq("price",300); 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
wrapper.select("pname as name") .eq("pname","张三") .or().eq("price",300); 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 |
le | 小于 | 例:le(“age”,18) —> age |
between | BETWEEN值1 AND值2 | 例:between(“age”,18,30) —> age between 18 and 30 |
notBetween | NOT BETWEEN值1 AND值2 | 例: notBetween(“age”,18,30) —> age not between 18 and 30 |
like | LIKE ‘%值%’ | 例: like(“name”,“王”) —–> name like ‘%王%’ |
notLike | NOT LIKE ‘%值%’ | 例: notLike (“name”,“王”) —> name not like ‘%王%’ |
likeLeft | LIKE ‘%值’ | 例:likeLeft (“name”,“王”) —–> name like ‘%王’ |
likeRight | LIKE’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 id in (select id from table where id |
notInSql | 字段NOT IN ( sql语句) | notInSql(“id”, “select id from table where id age not in (select id from table where id |
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 |
having | HAVING ( 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 |
and | AND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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