《數(shù)據(jù)挖掘cha》ppt課件-全文預(yù)覽
【正文】 ct Table time_key item_key branch_key location_key units_sold dollars_sold avg_sales Measures item_key item_name brand type supplier_key item branch_key branch_name branch_type branch supplier_key supplier_type supplier city_key city state_or_province country city 事實(shí)星座模式實(shí)例 time_key day day_of_the_week month quarter year time location_key street city province_or_state country location Sales Fact Table time_key item_key branch_key location_key units_sold dollars_sold avg_sales Measures item_key item_name brand type supplier_type item branch_key branch_name branch_type branch Shipping Fact Table time_key item_key shipper_key from_location to_location dollars_cost units_shipped shipper_key shipper_name location_key shipper_type shipper 一種數(shù)據(jù)挖掘查詢語(yǔ)言 : DMQL ? DMQL首先包括定義數(shù)據(jù)倉(cāng)庫(kù)和數(shù)據(jù)集市的語(yǔ)言原語(yǔ)，這包括兩種原語(yǔ)定義：一種是立方體定義，一種是維定義 ? 立方體定義 (事實(shí)表 ) define cube cube_name [dimension_list]: measure_list ? 維定義 (維表 ) define dimension dimension_name as (attribute_or_subdimension_list) ? 特殊案例 (共享維表的定義 ) ? 第一次作為維表定義 “ cube definition” ? 然后： define dimension dimension_name as dimension_name_first_time in cube cube_name_first_time 實(shí)例：使用 DMQL定義星型模式 define cube sales_star [time, item, branch, location]: dollars_sold = sum(sales_in_dollars), avg_sales = avg(sales_in_dollars), units_sold = count(*) define dimension time as (time_key, day, day_of_week, month, quarter, year) define dimension item as (item_key, item_name, brand, type, supplier_type) define dimension branch as (branch_key, branch_name, branch_type) define dimension location as (location_key, street, city, province_or_state, country) 實(shí)例：使用 DMQL定義雪花模式 define cube sales_snowflake [time, item, branch, location]: dollars_sold = sum(sales_in_dollars), avg_sales = avg(sales_in_dollars), units_sold = count(*) define dimension time as (time_key, day, day_of_week, month, quarter, year) define dimension item as (item_key, item_name, brand, type, supplier(supplier_key, supplier_type)) define dimension branch as (branch_key, branch_name, branch_type) define dimension location as (location_key, street, city(city_key, province_or_state, country)) 實(shí)例：使用 DMQL定義事實(shí)星座模式 define cube sales [time, item, branch, location]: dollars_sold = sum(sales_in_dollars), avg_sales = avg(sales_in_dollars), units_sold = count(*) define dimension time as (time_key, day, day_of_week, month, quarter, year) define dimension item as (item_key, item_name, brand, type, supplier_type) define dimension branch as (branch_key, branch_name, branch_type) define dimension location as (location_key, street, city, province_or_state, country) define cube shipping [time, item, shipper, from_location, to_location]: dollar_cost = sum(cost_in_dollars), unit_shipped = count(*) define dimension time as time in cube sales define dimension item as item in cube sales define dimension shipper as (shipper_key, shipper_name, location as location in cube sales, shipper_type) define dimension from_location as location in cube sales define dimension to_location as location in cube sales 度量的分類 ? 一個(gè)數(shù)據(jù)立方體的度量是一個(gè) 數(shù)值 函數(shù)，該函數(shù)可以對(duì)數(shù)據(jù)立方體的每一個(gè)點(diǎn)求值。這種模型可以以星型模式、雪花模式、或事實(shí)星座模式的形式存在。 ? 多維數(shù)據(jù)模型圍繞中心主題組織，該主題用 事實(shí)表表示 ? 事實(shí)表 包括事實(shí)的名稱或度量以及每個(gè)相關(guān)維表的關(guān)鍵字 ? 事實(shí) 指的是一些數(shù)字度量 多維數(shù)據(jù)模型 (2) —— 示例 time_key day day_of_the_week month quarter year time 維表 location_key street city state_or_province country location 事實(shí)表 Sales 事實(shí)表 time_key item_key branch_key location_key units_sold dollars_sold avg_sales 度量 item_key item_name brand type supplier_type item 維表 branch_key branch_name branch_type branch 維表 多維數(shù)據(jù)模型 (3) ? 在數(shù)據(jù)倉(cāng)庫(kù)中，數(shù)據(jù)立方體是 nD的 (n維） ? （關(guān)系表和電子表格是幾維的？） ? 示例 ? AllElectronics的銷售數(shù)據(jù)按維 time, item的 2D視圖 多維數(shù)據(jù)模型 (3) ? AllElectronics的銷售數(shù)據(jù)按維 time, item和 location的
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