【MySQL】sql_ Model mode

The reason for the problem is

   Today, Xiaobian encountered such a problem , The database code on the server can run normally , But after importing the database to the local database, the local database code cannot be run , Report the following error ：

The one that will report an error sql Statements are taken out and executed separately sql, Report the same question , But execute this on the server alone sql No problem. , So I checked online , It's a version problem .
   see mysql Database version ：SELECT VERSION() , The server version is 5.6.26, Local version is 5.7.22, The reason is because ： stay MySQL5.7 after ,sql_mode The default is ONLY_FULL_GROUP_BY,SQL Statement failed ONLY_FULL_GROUP_BY Semantic check so error report

Problem analysis ：

  ONLY_FULL_GROUP_BY：ONLY_FULL_GROUP_BY requirement select The columns queried in the statement must be explicit （ The same is true of other statements ）. With SQL sentence select columes from table group by list For example ：columns Must be Aggregation function Or must be group by The expression after list in , Otherwise, it will also report an error .insert、update、delete Statements will report errors （ But it doesn't affect SQL Execution of statements ）, Because the query operation will also be performed before the execution of these three statements

Illustrate with examples ：

    	SELECT count(1) FROM customer GROUP BY `name`; The SQL Successful implementation , because count Is an aggregate function ;
    
    　　SELECT * FROM customer GROUP BY `name`; The SQL Execution failure , because * Contains the primary key id, and group by The expression after does not contain id
    
    　　SELECT name FROM customer GROUP BY `name`; The SQL Successful implementation , because name Included in group by In the following expression 
    
    　　SELECT name, contact FROM customer GROUP BY `name`; The SQL Execution failure , because contact Not included in group by In the following expression 

Solution ：

 1. View local sql_mode:SELECT @@sql_mode

 2. modify sql_mode
   In the local mysql Found under installation directory my.ini, Query the contents sql_mode Remove the value ONLY_FULL_GROUP_BY Assign a value to sql_mode Value , restart mysql Service to take effect （ But I don't have it here my.ini file , But there is one my.ini.txt Text , The contents and my.ini Content is the same , Baidu learned that my.ini You have to build it yourself , So I built one by myself my.ini, take my.ini.txt Copy contents to recent files , Then set the sql_mode value ）

   You can also use set @@sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION' Change this service , But just restart mysql Service this setting will be invalidated