我就废话不多说了，大家还是直接看代码吧~

int count =hrDeliverEmployContractService.selectCount(new EntityWrapper<HrDeliverEmployContractEntity>().eq("pool_id",hrDeliverEmployContract.getPoolId()).andNew().lt("contract_start_date",hrDeliverEmployContract.getContractStartDate()).or().gt("contract_end_date",hrDeliverEmployContract.getContractEndDate()) );

对应的SQL

SELECT COUNT(1)FROM hr_deliver_employ_contractWHERE (pool_id = 1) AND (contract_start_date < '2018-07-01 00:00:00.0' OR contract_end_date > '2018-10-31 00:00:00.0');

补充：mybatis plus or使用

QueryWrapper queryWrapper = new QueryWrapper();queryWrapper .and(wrapper -> wrapper.isNull(“sim”).or().eq(“sim”, “”));queryWrapper .eq(“is_delete”, “0”);

对应sql语句

select * from vehicle where (sim is null or sim='') and is_delete=‘0'QueryWrapper queryWrapper = new QueryWrapper();queryWrapper .eq(“name”,“测试”).or().eq(“sim”,“2”);

对应sql语句

select * from vehicle where name=‘测试' or sim=‘2'

以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。