提高查询效率

专题/后端/2021.2.3好用的sql语句.md

@@ -2,4 +2,16 @@
 BEGIN
 SELECT SUM(power),yyyymmdd FROM powers WHERE monthweekday="HOURS" AND StartTime<=STR_TO_DATE(yyyymmdd,'%Y%m%d%H') AND EndTime>=STR_TO_DATE(yyyymmdd,'%Y%m%d%H') GROUP BY yyyymmdd;
 END
-```
+```
+
+```
+select count(*) from breakerdatas where mac='98CC4D213004'
+select count(*) from breakerdatas where mac='187ED53338C4'
+select count(*) from breakerdatas where mac='187ED53159E4'
+select count(*) from breakerdatas where mac='98CC4D213003'
+
+delete from breakerdatas where mac='187ED53338C4' and str_to_date(CreateTime, '%Y-%m-%d %H:%i:%s') <= str_to_date('2021-02-23 18:54:00', '%Y-%m-%d %H:%i:%s')
+
+select CreateTime, mac, addr from  breakerdatas where mac='187ED53338C4' and addr='1' and str_to_date(CreateTime, '%Y-%m-%d %H:%i:%s') >= str_to_date('2021-02-23 19:30:00', '%Y-%m-%d %H:%i:%s')
+```
+

专题/后端/DDD/9、EF Core使用Sql语句提高查询效率.md

@@ -0,0 +1,65 @@
+一种会报错的写法
+
+```
+var macBreakerDatas = _breakerDataRepo.GetAll().Where(t => t.mac == mac.Mac);
+
+var removedBreakerDatas = macBreakerDatas.Where(t => (DateTime.Now - DateTime.Parse(t.CreateTime)).Minutes >= 65);
+
+_breakerDataRepo.RemoveRange(removedBreakerDatas);
+```
+
+
+
+不报错，但查询效率慢
+
+```
+var macBreakerDatas = _breakerDataRepo.GetAll().Where(t => t.mac == mac.Mac);
+
+var removedBreakerDatas = macBreakerDatas.ToList().Where(t => (DateTime.Now - DateTime.Parse(t.CreateTime)).Minutes >= 65);
+
+_breakerDataRepo.RemoveRange(removedBreakerDatas);
+```
+
+
+
+修改基础设施层
+
+```
+    public interface IOpenBreakerDataRepository : IRepository<BreakerData, Guid>
+    {
+        IQueryable<BreakerData> GetAll();
+        IQueryable<BreakerData> GetAllBySql(string sql);
+    }
+    public class OpenBreakerDataRepository : Repository<BreakerData, Guid, OpenAPIContext>, IOpenBreakerDataRepository
+    {
+        public OpenBreakerDataRepository(OpenAPIContext context) : base(context)
+        {
+
+        }
+
+        public IQueryable<BreakerData> GetAll()
+        {
+            return DbContext.BreakerDatas.Where(t => true);
+            
+        }
+
+        public IQueryable<BreakerData> GetAllBySql(string sql)
+        {
+            return DbContext.BreakerDatas.FromSqlRaw(sql);
+        }
+    }
+```
+
+
+
+最后改成
+
+```
+string sixtyFiveAgoTimeStr = DateTime.Now.AddMinutes(-65).ToFullTimeStr();
+
+string rawSql = $"select * from  breakerdatas where mac='{mac.Mac}' and str_to_date(CreateTime, '%Y-%m-%d %H:%i:%s') <= str_to_date('{sixtyFiveAgoTimeStr}', '%Y-%m-%d %H:%i:%s')";
+
+var removedBreakerDatas = _breakerDataRepo.GetAllBySql(rawSql);
+_breakerDataRepo.RemoveRange(removedBreakerDatas);
+```
+