Simple to use Mysql database (b)

Mysql import .sql file

1. Access to the database (to import database)
2. Database has to import database .sql file name, not the new.
3. source path + filename

souce /home/robot/csql.sql

Database file .sql files in / home / robot directory

Delete the database data according to the time

DELETE FROM table WHERE time> = start time period AND <= End Time

 

Example:

mysql> DELETE FROM EnvironmentRealData WHERE SmpDatetime >= '2019-07-01 00:00:00' AND SmpDatetime <= '2019-07-02 00:00:00'

    -> ;

Query OK, 145 rows affected (0.01 sec)

 

mysql>

 

Ordered by time:

SELECT Rainfall FROM EnvironmentRealData ORDER BY SmpDatetime DESC；

SELECT SmpDatetime,Temprature,Humidity,WindSpeed,WindSpeed,WindDirection,Pressure,Rainfall FROM EnvironmentRealData ORDER BY SmpDatetime DESC

 

Inserting data from one table to another table:

Provided that: the same field two tables

Example: Create a table PointType you want to inherit Num Num field information devicespotrobotinfo table:

INSERT INTO target table (Field 1, Field 2, ...) SELECT field 1, field 2, ... FROM table origin

Into the database:
the INSERT the INTO PointType (the Num) from the SELECT the Num devicespotrobotinfo;

 

To delete a column is empty rows:

delete from PointType where Num is null;

 

Check this column Num repeating:

SELECT Num,COUNT(*) FROM PointType GROUP BY Num HAVING COUNT(*) > 1;

 

Delete duplicate data in the table:

DELETE FROM PointType WHERE Num IN( SELECT Num FROM( SELECT Num,COUNT(*) FROM PointType GROUP BY Num  HAVING COUNT(*) > 1 ) AS a ) LIMIT 1;