Ccom.mysql.cj.jdbc.exceptions.MySQLTransactionRollbackException: Lock wait timeout exceeded; try restarting transaction
Reasons for the problem
When optimistic locks modify data, the data version number has been modified, causing the modification to fail. When retrying the modification, each time the data read from the d ...
Added by xsist10 on Fri, 22 May 2020 21:51:58 +0300
---------------------------------------------------------------Table building----------------Determine whether the student table exists
declare num number; --Declare parameters num type number
select count(1) into num from user_tables where table_name='student';
if num>0 then
execute immediate 'drop table st ...
Added by crinkle on Thu, 21 May 2020 18:21:15 +0300
JDBC fixing steps:
Class.forName("com.mysql.cj.jdbc.Driver");//I don't know why com.mysql.jdbc.Driver will report an error. Please leave a message if you have any ...
Added by PHPfolife on Wed, 20 May 2020 17:31:54 +0300
In Oracle and SQL Server databases, you can set up some complex account password policies, such as locking an account more than N times after a failed login, so can you do the same in MySQL?The answer is that MySQL has similar capabilities, except in MySQL it delays the response time when its login fails beyond the threshold, instead of locking ...
Added by marco839 on Tue, 19 May 2020 20:23:28 +0300
In the previous article, I introduced the logic of relationship mapping in Entity Framework Core. The foreign key mapping of EF left in the previous article is not mentioned, that is, the relationship of one-to-one, one to many, many to one, many to many, etc. This article will give you a detailed analysis of how to set up these mappings.
1. Re ...
Added by imawake on Sun, 17 May 2020 08:59:50 +0300
1, Date and time functions
1. Function to get the current dateIt's the same. It's different
CURDATE() : Used to get the current date of the system
CURRENT_DATE() Used by the system to get the current date
mysql> select CURDATE(),CURRENT_DATE();
2. Get function of current time
CURTIME() : Used to get the current time of the system
Added by brighton on Thu, 14 May 2020 12:11:49 +0300
check constraint means to filter one or more columns according to certain preset rules. If the condition is true, the filtering succeeds; if the condition is false, the filtering fails and the failure code is returned to the client.
Why do you want to list and write this separately? You often encounter irregular SQL. In many cases, you can onl ...
Added by AndyB on Wed, 13 May 2020 12:25:22 +0300
1, Create your own database
Download and install MySQL
1.windows Download: http://dev.mysql.com/downloads/mysql/
2. Open the server: enter the bin directory of the download path in the terminal (cmd), and execute mysqld -- initialize executor to start the server and initialize, but an error will be reported. The reason is that there is no data ...
Added by _giles_ on Mon, 11 May 2020 07:51:35 +0300
7, MySQL client tools and SQL introduction
mysql client command introduction;
How to get help from mysql;
Management database of DDL statements;
DDL statement management table and case introduction;
Data in management table of DML statement;
SELECT to retrieve data;
2. mysql interface program and SQL introduction
mysql client comma ...
Added by jdimino on Fri, 08 May 2020 16:47:04 +0300
According to the real business requirements of a power grid company, this case realizes the difference aggregation calculation on the real-time flow through Blink SQL+UDAF. Through this case, the readers are familiar with UDAF writing and understand the method invocation relationship and order in UDAF. Thank you @ commander for your guidance in ...
Added by stalione on Fri, 08 May 2020 12:15:27 +0300