t, _ := time.ParseInLocation("2006-01-02 15:04:05", "2023-04-23 11:11:00", time.Local)
时间: 2024-05-23 11:10:52 浏览: 74
这是一个 Go 语言中的时间解析函数,它将字符串类型的时间 "2023-04-23 11:11:00" 解析成了一个 time.Time 类型的变量 t。其中 "2006-01-02 15:04:05" 是一个固定的时间格式,Go 语言中规定这个时间格式作为时间解析和格式化的标准格式。time.Local 表示使用本地时区。
相关问题
t3,err:=time.Parse("2006-01-02 15:04:05","2022-03-27 01:25:36")
根据引用\[1\]中的代码,t3,err:=time.Parse("2006-01-02 15:04:05","2022-03-27 01:25:36")的作用是将字符串"2022-03-27 01:25:36"解析为时间格式。如果解析成功,t3将会是一个表示该时间的Time类型变量,err将会是nil;如果解析失败,t3将会是一个零值的Time类型变量,err将会是一个非nil的错误。
#### 引用[.reference_title]
- *1* *2* *3* [Go语言标准库之time](https://blog.csdn.net/weixin_30687051/article/details/98583411)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v91^insertT0,239^v3^insert_chatgpt"}} ] [.reference_item]
[ .reference_list ]
SELECT b.CallerNum, b.Duration duration, min(b.CRT_TIME_) abnormalTime, count(b.CallerNum) abnormalCallNumber, count(b.CallerNum) abnormalCallTotal FROM basebill b left join billdetails b2 on b.base_bill_id =b2.base_bill_id where b2.area_code_ != 86 and b.billType = 1 and b.IS_DELETE_ = 0 and b.CRT_TIME_ >= '2023-06-06 13:00:00' and b.CRT_TIME_ <= '2023-06-06 15:00:00' and ( (b.Duration >=900) or (b.CallerNum in (SELECT b.CallerNum FROM basebill b left join billdetails b2 on b.base_bill_id =b2.base_bill_id where b2.area_code_ != 86 and b.billType = 1 and b.IS_DELETE_ = 0 and b.CRT_TIME_ >= '2023-06-06 13:00:00' and b.CRT_TIME_ <= '2023-06-06 15:00:00' GROUP BY b.CallerNum HAVING COUNT(b.CallerNum) >= 5)) or ((SELECT COUNT(*) FROM basebill b1 left join billdetails b2 on b1.base_bill_id =b2.base_bill_id where b2.area_code_ != 86 and b1.billType = 1 and b1.IS_DELETE_ = 0 and b1.CRT_TIME_ >= '2023-06-06 13:00:00' and b1.CRT_TIME_ <= '2023-06-06 15:00:00' and b1.CallerNum = b.CallerNum ) >= 10) ) group by b.CallerNum优化这条sql的查询速度,具体做法
具体做法如下:
1. 对where条件中的字段建立索引:针对b2.area_code_、b.billType、b.IS_DELETE_、b.CRT_TIME_、b.Duration、b.CallerNum等字段建立相应的索引,可以提高查询效率。
2. 避免使用子查询:将子查询改写成join操作,可以提高查询速度。例如:
```
SELECT b.CallerNum, b.Duration duration, min(b.CRT_TIME_) abnormalTime, count(b.CallerNum) abnormalCallNumber, count(b.CallerNum) abnormalCallTotal
FROM basebill b
LEFT JOIN billdetails b2 ON b.base_bill_id = b2.base_bill_id
LEFT JOIN (SELECT CallerNum, COUNT(*) AS cnt FROM basebill WHERE IS_DELETE_ = 0 AND CRT_TIME_ >= '2023-06-06 13:00:00' AND CRT_TIME_ <= '2023-06-06 15:00:00' GROUP BY CallerNum HAVING COUNT(*) >= 5) AS t1 ON b.CallerNum = t1.CallerNum
LEFT JOIN (SELECT CallerNum, COUNT(*) AS cnt FROM basebill WHERE IS_DELETE_ = 0 AND CRT_TIME_ >= '2023-06-06 13:00:00' AND CRT_TIME_ <= '2023-06-06 15:00:00' GROUP BY CallerNum HAVING COUNT(*) >= 10) AS t2 ON b.CallerNum = t2.CallerNum
WHERE b2.area_code_ != 86 AND b.billType = 1 AND b.IS_DELETE_ = 0 AND b.CRT_TIME_ >= '2023-06-06 13:00:00' AND b.CRT_TIME_ <= '2023-06-06 15:00:00' AND (b.Duration >= 900 OR t1.CallerNum IS NOT NULL OR t2.CallerNum IS NOT NULL)
GROUP BY b.CallerNum
```
3. 避免重复查询:在where条件和select语句中都有重复查询的情况,可以将重复查询的部分提取出来,减少查询次数。例如:
```
SELECT b.CallerNum, b.Duration duration, min(b.CRT_TIME_) abnormalTime, count(b.CallerNum) abnormalCallNumber, count(b.CallerNum) abnormalCallTotal
FROM basebill b
LEFT JOIN billdetails b2 ON b.base_bill_id = b2.base_bill_id
LEFT JOIN (SELECT CallerNum, COUNT(*) AS cnt FROM basebill WHERE IS_DELETE_ = 0 AND CRT_TIME_ >= '2023-06-06 13:00:00' AND CRT_TIME_ <= '2023-06-06 15:00:00' GROUP BY CallerNum HAVING COUNT(*) >= 5) AS t1 ON b.CallerNum = t1.CallerNum
LEFT JOIN (SELECT CallerNum, COUNT(*) AS cnt FROM basebill WHERE IS_DELETE_ = 0 AND CRT_TIME_ >= '2023-06-06 13:00:00' AND CRT_TIME_ <= '2023-06-06 15:00:00' GROUP BY CallerNum HAVING COUNT(*) >= 10) AS t2 ON b.CallerNum = t2.CallerNum
WHERE b2.area_code_ != 86 AND b.billType = 1 AND b.IS_DELETE_ = 0 AND b.CRT_TIME_ BETWEEN '2023-06-06 13:00:00' AND '2023-06-06 15:00:00' AND (b.Duration >= 900 OR t1.CallerNum IS NOT NULL OR t2.CallerNum IS NOT NULL)
GROUP BY b.CallerNum, b.Duration, abnormalTime
```
4. 分批查询:将查询时间段分成多个小段,避免一次查询过多数据,导致查询速度变慢。
5. 对于大表使用分区表:如果表中数据量较大,可以将表进行分区,以提高查询效率。
6. 定期清理无用数据:定期清理已经无用的数据,可以减少查询时的数据量,提高查询速度。
综上所述,以上优化方案可以针对不同的情况进行选择,以提高SQL语句的查询速度。