t1_history used to store the historical data of table t1, the data () may already exist in ti_history before the restart of mysqld, after the restart, we inserted () again. when the newly inserted () is migrated to the history table, the primary key constraint is violated.
2 Reasons for repeated values in the innodb auto-increment column
mysql> show create table t1/G;*************************** 1. row ***************************Table: t1Create Table: CREATE TABLE `t1` (`id` int(11) NOT NULL
;
Execute the show status operation to find that a large number of insert operations do not exist, and the time is greatly shortened (you need to first perform flush status)
The possible reason is that
(1) The default value of the table field is placed in the table's frm (. frm: table structure file. MYD: Table data file. MYI: Table index) file.
(2) alter column updates the
Core tips: This experiment demonstrates that when calling a method in a class, all methods imply a self parameter, and this parameter is passed as the first parameter of the object method...
First, create an empty form and put a button.The following two methods are declared under implementation:
// The external method declares only one parameter. In this case, the standard Object internal event Method tpolicyevent is declared. In this declaration, the sender corresponds to the object pointer
The workflow form uses Freemarker technology to bind the form to the background database, and each modification of the form definition will perform an ALTER operation on the database corresponding to the form. Today, the test system reports the following error when performing a save form definition operation:HTTP Status 500-statementcallback; Uncategorized SQLException for SQL [ALTER TABLEt_dymc_20140522141004 Change f_xqdbm f_xqdbm VARCHAR (COMMENT ' demand single code ';]; SQL state [HY000]; e
Get cookies
function Getcvar ($name) {
$re =";
if (isset ($_cookie[$name]) $_cookie[$name]!=") {
$re =$_cookie[$name];
}
return $re;
}
Hint function
function msg ($msg =',$burl =') {
echo ' ';
exit ();
}
Order number
if (!getcvar (' checkpaysession '))
{
MSG (' illegal operation ','/');
}
Else
{
Setcookie ("Checkpaysession", "" ");
}
Operational events such as the Act of landing judgment
Using system;using system.collections.generic;using system.text;using system.threading;using System.Windows.Forms; Using system.drawing;using system.diagnostics;namespace animatedtransform{static class Formtransform {Publi c static void Transformsize (Form frm, int newwidth, int newheight) {transformsize (frm, new Size (Newwidt H, Newheight)); } public static void Transformsize (Form
I wanted to make a small example of a simple single-piece design pattern (Singleton) in the morning, and there were some unexpected problems. My intention is to set up two form classes Form1 and Form2, put a button named Button1 on Form2, click Button1 will bring up the Form1 window case, and ensure that when you click Button1, no longer the second Form1 instance, Unless you turn off the Form1 instance and click Button1 again, it is guaranteed that only one Form1 instance will pop up (not in mod
; using system. collections. generic; using system. componentmodel; using system. data; using system. drawing; using system. LINQ; using system. text; using system. windows. forms; namespace windowsformsapplication1 {public partial class frmmain: FORM {public frmmain () {initializecomponent ();} private void frmmain_load (Object sender, eventargs E) {} private void file toolstripmenuitem_click (Object sender, eventargs e) {} private void Open main form 1toolstripmenuitem_click (Object sender, ev
a table structure update, not all of the update operations will take you a long time.For example, you would like to update the user table with the default password of "666666", which is usually done by
mysql> ALTER TABLE user
-> MODIFY COLUMN pwd VARCHAR not NULL DEFAULT ' 666666 ';
By show status you can see that a lot of inserts have been made during this operation, and when the number of users is large, such as millions, the thousands data will inevitably consume a lot of
Tags: library files nbsp Tables file ane HTM exists tmp mode(Turn from) https://www.cnblogs.com/DwyaneTalk/p/4113829.htmlData storage structure in one or two ways:Under MyISAM, every data table in the database has *.FRM, *. Ymi and *. Ymd three files, where *.FRM stores the table structure of a data table, *. Myi the index of the stored data table, *. Record data of myd data table;Under InnoDB, each data ta
InnoDB and MyISAM are two of the most common data storage engines for MySQL. Databases such as Oracle and SQL Server have not been researched, so the following is only for MySQL.Data storage structure in one or two ways:Under MyISAM, every data table in the database has *.FRM, *. Ymi and *. Ymd three files, where *.FRM stores the table structure of a data table, *. Myi the index of the stored data table, *.
case, if the original collection modifies one of the employee, the change also occurs in the collection of copies, But that's not what we want. In almost all cases, cloning should be independent of the original object. The way to avoid this problem is to use a deep copy collection that recursively copies the object until it accesses a primitive or immutable object. In this article, we will describe a method for deep copy collections, such as ArrayList or HashSet in Java. By the way, if you unde
Import java.io.*;public class employeetest{ public static void Main (String args[]) {/* Create two objects using a constructor */Employee Empone = new Employee ("RUNOOB1");Employee Emptwo = new Employee ("RUNOOB2"); Call the member methods of both objectsEmpone.empage (26);Empone.empdesignation ("Senior Programmer");Empone.empsalary (1000);Empone.printemployee (); Emptwo.empage (21);Emptwo.empdesignation ("rookie programmer");Emptwo.empsalary (500);Emptwo.printemployee ();}}Class employee{String
Know MySQL knows, in MySQL to build any data table, in its data directory corresponding to the database directory has a corresponding table of. frm files,. frm files are used to hold each data table metadata (meta) information, including the definition of table structure, etc. The frm file is not related to the database storage engine, which means that the data t
Background: Forms form1 and form2 form2 are opened by form1 (1, mode Form 2, non-mode). requirement: the textbox value of form2 is returned to the textbox of form1. Method 1: (mode form) form1. showdialog () Open form2view plaincopy to clipboardprint? Form1: public partial class form1: FORM {public form1 () {initializecomponent ();} private void button#click (Object sender, eventargs e) {form2 FRM = new form2 (this, textbox1.text); // construct form2
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