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Hierarchical data is defined as a set of data items that are correlated through hierarchical relationships. In hierarchical relationships, a data item is the parent or child of another item. Starting in 2008, SQL Server built-in hierarchyid data types make it easier to store and query hierarchical data. Hierarchy is actually a CLR data type.   ...

First, let's understand scalar quantum queries: sub-queries before from after select are called scalar quantum queries. For example, select num1,cal,(select name from t2 where t2.id = t1.id)from t1. The disadvantage of scalar quantum query is very obvious: the driver table is fixed by the appearance t1, and the result set value t2 returned by ...

SQL Terms/Concepts MongoDB Terms/Concepts Explanation/Explanation database database data base table collection Database tables/collections row document Data Record Row/Document column field Data Fields/Fields index index Indexes table joins Table connection, not supported by MongoDB primary key p ...

11g, can automatically manage sga,pga, known as amm MEMORY_MAX_TARGE: This parameter specifies the maximum value that MEMORY_TARGET can set. Memor_target specifies the available memory at the system level. It can reduce or increase the size of SGA and PGA as needed. In a text-based parameter file, if the MEMORY_MAX_TARGET parameter is exclude ...

Element Settings Continue MyBatis Configuration loading source code analysis: 1 private void parseConfiguration(XNode root) { 2 try { 3 Properties settings = settingsAsPropertiess(root.evalNode("settings")); 4 //issue #117 read properties first 5 propertiesElement(root.evalNode("properties")); 6 loadCustomVfs( ...

The Web SQL database API is not part of the HTML5 specification, but it is an independent specification that introduces a set of APIs that operate client database using SQL. Core approach The following are the three core approaches defined in the specification: openDatabase: This method creates a database object using an existing database or a ...

Have a good laugh [The weather was hot and the cabinet was turned upside down for half a day. Find out that all the famous short sleeves feel too high-profile to wear out, such as what China Telecom Ah Tianyi 4G Ah Mrs. Le Chi Jing Ah Lotus flower Ah Hai Tian soy sauce.The most precious one is that Stanley Compound Fertilizer tangled with Liu N ...

Preface Recent projects are written in a restful style. Sure enough, URLs are meaningful and functions can be inferred from urls. One of the biggest sensory differences between restful URLs and non-restful URLs is that there may be some variables in restful urls, such as the following: / check/api/user/12345/history, which is interpreted as: T ...

In fact, all operations recorded by MySQL binlog have corresponding event types. For example, DML operations in STATEMENT format correspond to QUERY_EVENT type, and DML operations in ROW format correspond to ROWS_EVENT type. QUERY_EVENT QUERY_EVENT records the operation of a transaction in the form of text. Events of type QUERY_EVENT are usu ...

This paper is divided into two parts: 1. Intellij Idea creates Web applications; 2. Develop a WEB application with additions, deletions and modifications and deploy it to the local server. Raw materials: Intellij IDE JDK Tomcat Mysql Navicat for MySQL Browser Develop related jar pa ...