Diese Seite beschreibt die External Table Funktionen in 11gR2. Oracle Database allows you read-only access to data in external tables. The external data can be queried directly and in parallel using SQL. When you use external tables to unload data, the metadata is automatically created based on the datatypes in the SELECT statement (sometimes referred to as the shape of the query). The example that will be developed first refers to the External Table using the ORACLE_LOADER driver.
External tables allow Oracle to query data that is stored outside the database in flat files. External Tables let you query data in a flat file as though the file were an Oracle table. In 9i, only read operations were permitted; in 10g, you can also write out data to an external table, although you can’t write to an existing table. This is an introduction to a new feature of external tables in 10g, namely the ability to unload data from the database using SQL. Introduced in 9i, external tables provided a new means of reading flat file data without first loading it into a staging table.
Once an external table is created, loading data from the flat-file to the database is as. External tables are an useful feature which allows us to read flat-files directly using SQL just like normal Oracle tables. External tables works well if the database is running on 10g on windows- but errors keep happening when it is ran on Linux. Starting with version Oracle Database 10g, external tables can be written to as well as read from. To unload data using an external table, utilize the Oracle Database 10g new feature called the oracle_datapump access driver. In versions prior to Oracle Database, the only access method available for Oracle external tables was oracle_loader, essentially a SQL Loader interface that only allowed reading from external tables into the Oracle database.
When you query the table, oracle reads the external table and returns the results just as if the data had been stored with in the database. To access external files from within oracle, you must first use the create directory command to define a directory object pointing to the external file location. OBIEE 10g Production Installation Steps and Screen. Better Understanding of External Tables in Oracle10g. Topics of Discussion History of External File usage? Reading External Tables? How to import third line only in oracle using sql loader or external table. I have this data to load in to oracle i use external table concept to load the data. any idea how to load only the third line from the source? This is the data in txt externally located. Prior to Oracle Database 10g, external tables were read-only. Oracle 10g and 11g offer some new functionality for external tables. 10g. The ability to write to an external table is restricted to the use of the create table as select command only; therefore, insert, update, and delete operations are not supported. 10g Release 1 (10.1) Part Number B10736-01 Home Book List Contents Index Master Index Feedback Previous Next View PDF. When using Oracle Database as a transformation engine, a common strategy is to implement each transformation as a separate SQL operation and to create a separate, temporary staging table (such as the tables new_sales_step1 and new_sales_step2 in Figure 14-1) to store the incremental results for each step. Oracle’s external table feature enables you to use external data as a virtual table that can be queried and joined directly and in parallel without requiring the external data to be first loaded in the database.