oraclesql基礎(chǔ)知識(shí)論述(參考版)
2025-01-27 09:47本頁(yè)面
【正文】 演講完畢，謝謝觀看！。 A subquery answers multiplepart questions. For example, to determine who works in Taylor39。 ?right outer joinSELECT , FROM departments d RIGHT OUTER JOIN employees e ON = ORDER BY 。R%39。 works for 39。s select list can select any columns from any of these tables. If any two of these tables have a column name in mon, then you must qualify all references to these columns throughout the query with table names to avoid ambiguity.Join condition:Most join queries contain WHERE clause conditions that pare two columns, each from a different table. Such a condition is called a join condition. To execute a join, Oracle bines pairs of rows, each containing one row from each table, for which the join condition evaluates to TRUE. The columns in the join conditions need not also appear in the select list.(1)EquijoinsSELECT last_name, job_id, , department_name FROM employees, departments WHERE = 。?About SQL Expressions?Simple Expressions?Compound Expressions ?CASE Expressions ?CURSOR Expressions ?Datetime Expressions?Function Expressions ?INTERVAL Expressions?Object Access Expressions ?Scalar Subquery Expressions?Type Constructor Expressions?Variable Expressions?Expression Lists?About SQL Conditions?Comparison Conditions ?Logical Conditions?Membership Conditions?Range Conditions?Null Conditions ?EXISTS Conditions ?LIKE Conditions SQL DDL子句?allocate_extent_clause?constraints?deallocate_unused_clause?file_specification?logging_clause?parallel_clause?physical_attributes_clause?storage_clause使用在 :alter table,alter index使用在 :alter table,alter index使用在 :create tablespace,create temporary tablespaceAutoextend_clause:使用在 :create table,create index使用在 :create tablespace,create table,create indexExtent_management_clause::=Segment_management_clause::=(只有永久的 ,本地管理的表空間才有關(guān)的 )create_temporary_tablespace::=temp_tablespace_extent::=Table_index_clause::=. SQL查詢(xún)和子查詢(xún)?About Queries and Subqueries?Creating Simple Queries ?Hierarchical Queries ?The UNION [ALL], INTERSECT, MINUS Operators?Sorting Query Results?Joins?Using Subqueries?Unnesting of Nested Subqueries ?Selecting from the DUAL Table?Distributed QueriesA join is a query that bines rows from two or more tables, views, or materialized views. Oracle performs a join whenever multiple tables appear in the query39。INTERSECTSELECT product_id FROM inventoriesINTERSECTSELECT product_id FROM order_items。OE/OEUNIONselect location_id, department_name Department, to_char(null) Warehousefrom departmentsunionselect location_id, to_char(null) Department, warehouse_namefrom warehouses。INTERSECTSELECT product_id FROM inventoriesINTERSECTSELECT product_id FROM order_items。 SQL操作符?About SQL Operators?Arithmetic Operators?Concatenation Operator?Set Operators?UserDefined OperatorsUnionUnion allIntersectMinusOE/OEUNIONselect location_id, department_name Department, to_char(n
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