caohong286的专栏

Performance Tuning with the Model Clause  Model子句的性能调优   (page 293)    As with all SQL, sometimes you need to tune statements using the Model clause. To that end, it helps to know how to read ex...

NULLs   (page 291)    In SQL statements using Model SQL, values can be null for two reasons: null values in the existing cells and references to non-existent cells. I will discuss the later sc...

Lookup Tables     查找表(page 290)    You can define a lookup table and refer to that lookup table in the rules section. Such a lookup table is sometimes termed a  reference table . Reference tab...

Iteration   迭代  (page 287)    Iteration provides another facility to implementing complex business requirements using a concise Model SQL statement.  A block of rules can be executed in a loop...

Evaluation Order   求值顺序    (page 282)      Multiple rules can be specified in the rules section, and the rules can be specified with dependencies betweene them. The rule evaluation sequence can ...

Returning Updated Rows   返回更新的行      (page 280)    In Listing 9-7, just four rows were returned even though there are rows for other weeks. The clause RETURN UPDATED ROWS  controls this behavi...

Positional and Symbolic References     位置和符号引用   (page 277)    As discussed previously, the CV function provides the ability to refer to a single cell. It is also possible to refer to an ind...

Inter-Row Referencing via the Model clause 用Model子句行间引用  (page 274)    In a conventional SQL statement, emulating the spreadsheet described in Listing 9-1 is achieved by a multitude of self-...

The Model Clause    Model子句   (page 273)Riyaj Shamsudeen     The Model clause introduced in the Oracle Database version 10g provides an elegant method to replace the spreadsheet. With the Mo...

Subquery Factoring    子查询分解    (page 303)    In a business setting, requirements are complex and multiple levels of aggregation are often needed. When writing complex queries, you can often co...

Aggregation   聚合    (page 285)    Data aggregation is commonly used in the data warehouse queries. The Model clause provides the ability to aggregate the data using aggregate functions over th...