I want to try some demo at random, but it got stuck when I started designing the database. The following is the relational model I derived. Please help me to see what is unreasonable, regardless of the data type. In addition, there is a class_teacher_co...
the company is the server placed in its own computer room, and the domain name is purchased on name and godday. Now I want to put it on record. How to operate it? most of the servers given online are too general ....
does the, CASE WHEN THEN statement have to be used with the select statement in SQL server? declare @i int set @i=100 case @i when 100 then print 100 when 200 then print 200 else print 300 end the above statement reported an error ...
I used the following statement to query, although I found a historical SQL record. SELECT st.text as sql_statement, qs.creation_time as plan_last_compiled, qs.last_execution_time as plan_last_executed, qs.execution_count as plan_executed_count...
I now have multiple tables that generate one table every day from July 1 to December 30, and now my boss asks me to summarize the table contents of each month. The database table is just like in the picture. I wonder if it is possible to use a SQL state...
start with in Oracle. How to optimize connect by prior? an address table has a total of 8-level addresses. Pass in the address id, to query all the superior addresses. The code is . select address_id addressId, address_name addressName, ...
what do you usually consider when adding an index? I usually add an index by querying a few fields in the where clause and adding an index to those fields. ...
first of all, I want to query the department to which the user belongs select * from dept where id in (select deptId from employee where id= 00 ) the above statement is not good. If you want to achieve such a result, how can you use SQL statement to...
use sql to query the database, and if there is no data in the field, set the data in the field to a certain value? How to write such sql ? ...
1. For example, there are two formats for records in the create_date field: 2018-10-10 09:08:07 and 2018-10-10 09-08-07 how to find out two different formats in the sql statement delete the format 2018-10-10 09-08-07 ...
Table relationship: question: how to query the data shown in the figure using native sql statements? expected data structure (the list item of the product appears as a nested object): { "category": [ { "id": 1,...
Table structure: create table test_tmp ( id int, log_time datetime, item varchar (10) ) create table test_d ( id int, name varchar (10) ) Test data: insert into test_d values (1, hh ); insert into test_d values (2, xx ); insert into test_...
after Sping Boot integrates Mybatis, set console output to execute SQL logging: level: com...dao: debug this package is full of mapper interfaces generated by mybatis generator, and the console can output SQL. in addition, I have defined a gene...
now you need to intercept all the execution sql of ibatis and record them in the database, but you can t find the relevant interceptor of ibatis (only the interceptor of mybatis). How to get all execution sql and record it? ...
use leftJoin multi-table join lookup. Finally, a field in select is a field from count in one of the right tables, but if there is no count data in that table, the entire query will lose the result. Now you want to keep the data in the left table if the...
Let me ask you a question. The name of T1 does not exist in T2. It doesn t come around a bit. The name in T2 not in T1 is still not correct ....
question: query all data whose RUN_TYPE is 1 and SWITCH_TYPE is 1 in adjacent time (RUN_DATE) of ID. data sheet: Tunable data, as shown in the figure. :RUN_TYPE1SWITCH_TYPE1IDRUN_DATE SQL:SELECT * FROM T_DATA a WHERE a.SWITCH_TYPEIN( 1 ) AND (a...
1 the result is that true, is tested after using where true all conditions are null the first condition is null all are not null can get the right result, and where 1 can get the right result. After google, it is found that no one has done so....
has two columns of data: all is the cumulative total amount of prizes issued, and use is the amount used id all use 11500 220000 320000 420000 520000 6500 written with sqlserver sql sentence. One record is extracted from these six pieces of data...
There are 1000 pieces of data in the user_default_avatar table, but the result of the query is always greater than 500 instead of floating around 500? select * from user_default_avatar order by rand() limit 100; ...
demand FooService: methodA methodB methodC An and B C are mutually exclusive, that is, they cannot operate at the same time, but B and C can operate at the same time obviously synchronized does not support it because it is mutually ex...
in the online springcloud tutorials, we often see the following code block under the root pom <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud< grou...
<?php $a = array(); $b = $a[ test ]; ?> when the above code is executed alone, it will only be reported: PHP Notice: Undefined index: test in private var folders lr hbwptx4s1017kl_hlr4d9b4r0000gn T CodeRunner Untitled.php on line 3 ...
imitate processON, to do a small example of mouse drag, you can press and hold the four corners to change the size, you can rotate after rotation, I calculate the new width and height, based on the matrix matrix of transform, because I see that the rot...
@ click.stop is useless. ...