mysql 常用函数以及常见查询语句

MySQL 常用函数

1、数据库中取昨天的日期

mysql> select date_sub(current_date(),interval 1 day);
+-----------------------------------------+
| date_sub(current_date(),interval 1 day) |
+-----------------------------------------+
| 2016-01-11                              |
+-----------------------------------------+
1 row in set (0.00 sec)

2、数据库中取明天的日期

mysql> select date_add(current_date(),interval 1 day) ;
+-----------------------------------------+
| date_add(current_date(),interval 1 day) |
+-----------------------------------------+
| 2016-01-13                              |
+-----------------------------------------+
1 row in set (0.00 sec)

3、IPV4和整形之间相互转化

mysql> select inet_aton(‘192.168.2.18‘);
+---------------------------+
| inet_aton(‘192.168.2.18‘) |
+---------------------------+
|                3232236050 |
+---------------------------+
1 row in set (0.00 sec)

mysql> select inet_ntoa(3232236050);
+-----------------------+
| inet_ntoa(3232236050) |
+-----------------------+
| 192.168.2.18          |
+-----------------------+
1 row in set (0.00 sec)

4、日期转化为UNIXTIME

mysql> select unix_timestamp(‘2016-01-12 11:22:23‘);
+---------------------------------------+
| unix_timestamp(‘2016-01-12 11:22:23‘) |
+---------------------------------------+
|                            1452568943 |
+---------------------------------------+
1 row in set (0.00 sec)

5、UNIXTIME转化为日期

mysql> select from_unixtime(1452568943);
+---------------------------+
| from_unixtime(1452568943) |
+---------------------------+
| 2016-01-12 11:22:23       |
+---------------------------+
1 row in set (0.00 sec)

MySQL 常用查询语句

1、csv文件导出导入

## 将数据导出成csv
select * from myid into outfile ‘/tmp/test.sql‘;
## 将csv导入到表中
load data local infile ‘/tmp/test.sql‘ ignore into table NL_U_MOBILE_URI_TEST fields terminated by ‘\t‘ lines terminated by ‘\n‘;

2、使用profile分析sql的执行过程

mysql> set profiling=1;

mysql> select  sum(error_count) as error_count, mobile_app_version_id as mobile_app_version_id from NL_MOB_APP_ERROR_TRACE where  timestamp >= ‘2015-05-27 09:00:00‘ AND timestamp < ‘2015-06-03 09:00:00‘ and error_code in (  904  )  and request_url_id = -859289307 and mobile_app_id = 6589  group by mobile_app_version_id order by error_count desc;

mysql> show profiles;
mysql> select state,sum(duration) as Total_R, round(100*sum(duration)/(select sum(duration) from information_schema.profiling where query_id=@query_id),2) as Pct_R, count(*) as Calls, sum(duration)/count(*) as "R/Call" from information_schema.profiling where query_id=@query_id group by state order by Total_R desc;
+--------------------------------+------------+-------+-------+----------------+
| state                          | Total_R    | Pct_R | Calls | R/Call         |
+--------------------------------+------------+-------+-------+----------------+
| Copying to tmp table           | 149.779769 | 99.41 |     1 | 149.7797690000 |
| statistics                     |   0.893111 |  0.59 |     1 |   0.8931110000 |
| System lock                    |   0.000117 |  0.00 |     2 |   0.0000585000 |
| checking query cache for query |   0.000090 |  0.00 |     1 |   0.0000900000 |
| Opening tables                 |   0.000062 |  0.00 |     1 |   0.0000620000 |
| removing tmp table             |   0.000051 |  0.00 |     1 |   0.0000510000 |
| freeing items                  |   0.000049 |  0.00 |     1 |   0.0000490000 |
| init                           |   0.000048 |  0.00 |     1 |   0.0000480000 |
| Creating tmp table             |   0.000044 |  0.00 |     1 |   0.0000440000 |
| optimizing                     |   0.000039 |  0.00 |     1 |   0.0000390000 |
| preparing                      |   0.000039 |  0.00 |     1 |   0.0000390000 |
| closing tables                 |   0.000036 |  0.00 |     1 |   0.0000360000 |
| Sorting result                 |   0.000022 |  0.00 |     1 |   0.0000220000 |
| starting                       |   0.000020 |  0.00 |     1 |   0.0000200000 |
| Sending data                   |   0.000016 |  0.00 |     1 |   0.0000160000 |
| Opening table                  |   0.000013 |  0.00 |     1 |   0.0000130000 |
| logging slow query             |   0.000011 |  0.00 |     2 |   0.0000055000 |
| checking permissions           |   0.000008 |  0.00 |     1 |   0.0000080000 |
| end                            |   0.000006 |  0.00 |     2 |   0.0000030000 |
| Waiting on query cache mutex   |   0.000006 |  0.00 |     2 |   0.0000030000 |
| query end                      |   0.000004 |  0.00 |     1 |   0.0000040000 |
| cleaning up                    |   0.000002 |  0.00 |     1 |   0.0000020000 |
| executing                      |   0.000002 |  0.00 |     1 |   0.0000020000 |
| Waiting for query cache lock   |   0.000002 |  0.00 |     2 |   0.0000010000 |
+--------------------------------+------------+-------+-------+----------------+

mysql> set profiling=0;

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原文：http://quenlang.blog.51cto.com/4813803/1734272