Oracle table cast collection updating type using table cast

posted by | Leave a comment

Unfortunately, the TO_LOB function cannot be used in SQL outside of a Create Table As Select (CTAS) statement, as the following example demonstrates.For volatile data, therefore, we might want to consider the remaining workarounds, as they do not involve copying data to a static target.The LONG and LONG RAW datatypes have been deprecated in favour of LOBs for many Oracle versions, yet they still exist in the data dictionary and legacy systems.For this reason, it is still quite common to see questions in Oracle forums about querying and manipulating LONGs.We can see that the USER_TAB_COLUMNS view only lists the first two columns as being mandatory.These two columns were defined with the "NOT NULL" keywords during table creation and this appears to be the only method that this view understands (note that this view uses USER_TAB_COLS which in turn decodes the COL$. Therefore, to solve this problem, we need to look elsewhere, so we'll use the USER_CONSTRAINTS view, described as follows. Type ---------------------------------- -------- ----------------- OWNER VARCHAR2(30) CONSTRAINT_NAME NOT NULL VARCHAR2(30) CONSTRAINT_TYPE VARCHAR2(1) TABLE_NAME NOT NULL VARCHAR2(30) SEARCH_CONDITION LONG R_OWNER VARCHAR2(30) R_CONSTRAINT_NAME VARCHAR2(30) DELETE_RULE VARCHAR2(9) STATUS VARCHAR2(8) DEFERRABLE VARCHAR2(14) DEFERRED VARCHAR2(9) VALIDATED VARCHAR2(13) GENERATED VARCHAR2(14) BAD VARCHAR2(3) RELY VARCHAR2(4) LAST_CHANGE DATE INDEX_OWNER VARCHAR2(30) INDEX_NAME VARCHAR2(30) INVALID VARCHAR2(7) VIEW_RELATED VARCHAR2(14) The USER_CONSTRAINTS view exposes a LONG column named SEARCH_CONDITION and this column contains the NOT NULL constraints in our table.We therefore need to find workarounds, which is of course the subject of this article.

In the following example, we will loop through the NULLABILITY_VIEW data and interrogate the SEARCH_CONDITION column for NOT NULL constraints.

TABLE_NAME COLUMN_NAME SEARCH_CONDITION -------------------- --------------- ------------------------------ NULLABILITY_TEST C1 "C1" IS NOT NULL NULLABILITY_TEST C2 "C2" IS NOT NULL NULLABILITY_TEST C3 c3 IS NOT NULL NULLABILITY_TEST C4 c4 IS NOT NULL 4 rows selected.

As with TO_LOB, we have identified all mandatory columns, but this time without having to materialise the NULLABILITY_VIEW data.

These questions are prompted because the LONG datatype is extremely inflexible and is subject to a number of restrictions.

In fact, it's fair to say that there isn't much we can do with a LONG value once it has been inserted into a table.

Leave a Reply

  1. dumb dating mistakes 19-Aug-2016 22:49

    GIVE you 30 FREE VIP credits just for signing up and verifying your age with a validated credit card.

  2. sex dating in ellsworth maine 24-Feb-2017 19:07

    According to our google pagerank analysis, the url currently has a pagerank of /10.

  3. Web cam uome sex 20-Aug-2017 19:47

    Pettyfer also starred in the 2012 film Magic Mike, and played a supporting role in the 2013's film The Butler. As a schoolboy, he performed in plays, including in the role of Willy Wonka in a production of Charlie and the Chocolate Factory, Jack in his school play "Jack and the Beanstalk" and Robin Hood in the adaptation of The Adventures of Robin Hood (1938).

  4. Adult dating nulled 09-Nov-2017 02:12

    The Berwick Street factory moves quickly into production of drum kits and portable tuned instruments.

  5. London sex mature 22-Sep-2017 15:22

    This exploration of the intersection of sex and technology is told through the stories of the people whose lives are defined by ...

  6. tripp lite snmpwebcard updating tool 19-Jun-2017 22:56

    You might find out that you absolutely love it and you meet someone early on.

who is david gallagher dating