1. Obtain the default values of all tables in the database: The code is as follows:Copy code SelectT3.name as table name, t1.name as field name, t2.text as default value, t4.nameFrom syscolumns t1, syscomments t2, sysobjects t3, sysobjects t4Where t1.cdefault = t2.id and t3.xtype = 'u' and t3.id = t1.idAnd t4.xtype = 'd' and t4.id = t2.id; 2.
| |+----+-------------+-------+-------+-------------------+---------+---------+-------+------+-------+
(3). Eq_ref
Read a row from the table for each combination of rows from the previous table. This may be the best join type, except for the const type. It is used in all parts of an index to be joined and the index is unique or primary KEY.
Eq_ref can be used to compare indexed columns with the = operator. A comparison value can be a constant or an expression that uses a column of a table th
The connect by level syntax is particularly useful when constructing a large amount of data. However, if you do not really understand the meaning of the syntax, misuse will lead to the production of a large amount of data, generally, the incorrect understanding is the Cartesian product of the Base record and the base record. Cartesian product is correct, but not both of them are the base record. One of them is the record of the last level, it is important to know this, otherwise it will produce
MvcView directory and we can see
Here is a view template, including C # and VB. Since the project uses C #, copy C # To the MvcView directory:
(Note: You need to copy Imports. include. t4 and ModelMetadataFunctions. cs. include. t4 at the same time, because the project requires these files to generate views using the base frame)
Open one of the templates and find that the Base Frame uses the
EffectThe disadvantage of using fragment to achieve tab is that you cannot swipe. But should also calculate the merit, the concrete scene can choose freely.Complete code: Imooc-tab022fragment, in my Baidu Cloud network disk.Mainacgtivity.java1 Packagecom.example.imooc_tab02;2 3 ImportAndroid.os.Bundle;4 Importandroid.support.v4.app.FragmentActivity;5 ImportAndroid.support.v4.app.FragmentManager;6 Importandroid.support.v4.app.FragmentTransaction;7 ImportAndroid.view.View;8 ImportAndroid.view.Vie
//chained storage of trees--three-prong notation#include #include#includestring.h>typedefstruct_treenode{//data fields intdata; //pointer Field struct_treenode * LEFTCHILD;//left child pointer struct_treenode * RIGHTCHILD;//Right Child pointer struct_treenode * parent;//Parent pointer---- more than a binary representation of a parent pointer }treenode, *Treenodepointer;voidTest1 () {//defining the structure body objectTreeNode T1, t2, T3, T4
transaction t have been written to the log file but may not have been written to the databaseOracle writes to the database at the time this checkpoint is established!There is no need to perform a redo operation on the transaction T while the recovery process is in progressRecovery strategy using checkpointsT1: Submit before CheckpointT2: Start execution before checkpoint, submit before point of failure after checkpointT3: Start execution before checkpoint, not completed at point of failureT4: S
| Simple | T3 | const | primary,idx_t3_id | PRIMARY | 4 | const | 1 | | +----+-------------+-------+-------+-------------------+---------+---------+-------+------+-------+(3). Eq_refFor each row combination from the preceding table, a row is read from the table. This may be the best type of join, except for the const type. It is used in all parts of an index to be joined and the index is unique or primary KEY.Eq_ref can be used for indexed columns that use the = operator
,Rds.sales_order T1,Allocate_date_dim T2,rds.cdc_time T4where T0.order_number = t1.order_number and t1.order_status = ' A 'and To_date (t1.status_date) = T2.allocate_dateand T1.entry_date gt;= T4.last_load and T1.entry_date
DELETE from Sales_order_fact WHERE sales_order_fact.order_number in (SELECT order_number from TMP);INSERT into Sales_order_fact SELECT * from TMP;
DROP TABLE IF EXISTS tmp;CREATE TABLE tmp asSelect T0.order_number Order_number,T
(1,1); var PB = new Point (1,1); var pc = PA; Then: PA!=PB; PA!==PB; Pa==pc; Pa===pc; var arr1 = [1,2,3]; var arr2 = [1,2,3]; Arr1!=arr2, ARR1!==ARR2 Have to say 0, false, null, undefined var t1 = 0; var t2 = false; var t3 = null; Var T4; Then: t1==t2;t1!==t2; T1!=t3; t1!==t3; T1!=t4; t1!==t4; T2!=t3; t2!==t3; T2!=
JavaScript Object ComparisonsComparison character:==,!=,===,!==,>=,= = always try to compare them straight, if the type is not the same, always try to convert.= = = More identity, no conversion on the comparison= = If it is the base type (string, number, Boolean), compare their values,var a = "123";var B = 123;Then (a==b) = true;(a===b) = false;If it is object, array, function type, compare their reference. Only if their reference is equal is true.function Point (x,y) {this.x = x;This.y = y;};
, FC, S,ftype,fcount,i,j,k
Dim T1,T2,T3,T4,T5
Dim Imonth,iday
Slistfile = ""
Set fso = CreateObject ("Scripting.FileSystemObject")
Set f = fso. GetFolder (Sshowpath)
Set FC = F.files
Fcount = Fc.count
ReDim Arrfiles (fcount,5)
ReDim ArrFiles2 (fcount,5)
I=0
' Sort
For each F1 in FC
Ftype = Right (F1.name,len (f1.name)-instrrev (F1.name, "."))
Arrfiles (i,0) = F1.name
Arrfiles (i,1) = Ftype
Arrfiles (i,2) = F1.size
Arrfiles (i,3) = F1.
.
retrieving an entire tree
Typically, the first task in dealing with layered data is to render a complete tree in some form of indentation. For this reason, the usual practice in pure SQL encoding is to use a self-join:
SELECT T1.name as Lev1, t2.name as Lev2, t3.name as Lev3, t4.name as Lev4
From category as T1
Left JOIN category as t2 on t2.parent = t1.category_id
Left JOIN category as T3 on t3.parent = t2.category_id
Left JOIN category as
this case with the following experiment. First set up the relevant test table:
ALTER DATABASE Add supplemental log data (primary Key,unique index) columns;CREATE TABLE test (t1 int, t2 int, t3 int, T4 int);ALTER TABLE TEST ADD constraint Pk_t1 primary key (T1); --Add primary keyThen use a loop to insert a certain amount of dataUpdate test set t2=10; Commit --Update data
Using the LOGMNR tool to analyze previous operations
)); Query OK, 0 rows affected (0.24 sec) mysql> desc t3;+-------+----------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra |+-------+----------+------+-----+---------+-------+| ID | Int (11) | YES | MUL | NULL | || name | char (15) | YES | | NULL | |+-------+----------+------+-----+---------+-------+2 rows in Set (0.01 sec) Common index constraint keys are: Primary key Unique Key,The normal indexes are: IndexThe specified field is an indexed field af
Js object comparison implementation code.
Javascript Object comparisonComparison OPERATOR: = ,! =, = ,! ==, >=, = Always try to compare them straight, if the types are different, always try to convert.=== Comparison same, comparison without conversion= If it is a basic type (string, number, boolean), compare their values,Var a = "123 ";Var B = 123;Then (a = B) = true;(A = B) = false;If it is object, array, function type, compare their reference. Only when their reference is equal is true.Functio
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