tailieunhanh - Oracle Built−in Packages- P90

Oracle Built−in Packages- P90: Ah, for the good old days of Version of PL /SQL! Life was so simple then. No stored procedures or functions and certainly no packages. You had your set of built−in functions, like SUBSTR and TO_DATE. You had the IF statement and various kinds of loops. With these tools at hand, you built your batch−processing scripts for execution in SQL*Plus, and you coded your triggers in SQL*Forms , and you went home at night content with a good day's work done. | Appendix A What s on the Companion Disk DBMS_ROWID nonprogram elements Table lists the named constants defined by the DBMS_ROWID package for use with its programs. Table DBMS_ROWID Constants Name Type Description ROWID_TYPE_RESTRICTED A ROWID type integer constant assigned the value of 0. ROWID_TYPE_EXTENDED A ROWID type integer constant assigned the value of 1. ROWID_IS_VALID A ROWID verification result integer constant assigned the value of 0. ROWID_IS_INVALID A ROWID verification result integer constant assigned the value of 1. ROWID_OBJECT_UNDEFINED An object type indicating that the object number is not defined for restricted ROWIDs integer constant assigned the value of 0. ROWID_CONVERT_INTERNAL A ROWID conversion type integer constant assigned the value of 0. ROWID_CONVERT_EXTERNAL A ROWID conversion type integer constant assigned the value of 1. ROWID Concepts This section offers a quick overview of the Oracle ROWID. You can get much more extensive information on ROWIDs from the Oracle documentation. In the Oracle RDBMS ROWID is a pseudocolumn that is a part of every table you create. The ROWID is an internally generated and maintained binary value that identifies a row of data in your table. It is called a pseudocolumn because a SQL statement includes it in places where you would normally use a column. However it is not a column that you create for the table. Instead the RDBMS generates the ROWID for each row as it is inserted into the database. The information in the ROWID provides the exact physical location of the row in the database. You cannot change the value of a ROWID. You can use the ROWID datatype to store ROWIDs from the database in your PL SQL program. You can SELECT or FETCH the ROWID for a row into a ROWID variable. To manipulate ROWIDs in Oracle8 you will want to use the DBMS_ROWID package described in this chapter. In Oracle7 you will use the ROWIDTOCHAR function to convert the ROWID to a fixed-length string and then