Cursor for updating in oracle relatedwww cartagenadating com
After more and more reads about BULK COLLECT and FORALL and their performance improvements I decided to have a closer look on it by myself to see how powerful they really are.
So I built a little test-case which inserts all entries from the all_object view into another table.
This clause can also be extended to lock only the intended table in the SELECT query containing more than one table in joins using the FOR UPDATE OF clause.
This clause becomes meaningless if we use a single table SELECT clause as the minimum Oracle has provided us with the WHERE CURRENT OF clause for both DELETE and UPDATE statements inside a cursor’s range to make changes to the last fetched row(s) from the cursor with an ease.
The inserts happens on three different ways: First way is a simple cursor over the view and a insert in a loop with FETCH into local variables.
SQL Ok so now we need 10 seconds for the run with the bulk but we sill need 21 seconds for the cursor!In such a case, an another approach with bulk collectiong in chunks is required.-- EDIT --- how to store sequence values ------- I assume that the table create or replace PROCEDURE pro_cedure( p_dept_id number ) IS TYPE changed_table_type IS TABLE OF changed%ROWTYPE; changed_buff changed_table_type; BEGIN SELECT deptno, comm, extra, sequence_name.nextval BULK COLLECT INTO changed_buff FROM emp WHERE comm IS NULL AND extra IS NOT NULL AND deptno = p_dept_id FOR UPDATE; UPDATE emp SET comm = extra WHERE comm IS NULL AND extra IS NOT NULL AND deptno = p_dept_id; FORALL i IN 1 ..In the below example, the cursor CUR is associated with a SELECT statement having the tables EMPLOYEES and joined in its FROM clause. EMPLOYEE_ID clause in the below snippet locks up only rows of the EMPLOYEES table, thus making the DEPARTMENTS table available for modification to the other session users. For this, the cursor CUR is associated with a SELECT statement joining the EMPLOYEES and the DEPARTMENTS tables with a FOR UPDATE OF clause on the employee ID.When we try to update the salary column of the EMPLOYEES table using the WHERE CURRENT OF clause, the block fails with an ORA-01410: invalid ROWID error as there is no way to specify the This scenario can be manhandled by fetching the rowid of the intended table in the cursor associated SELECT statement and using it in the WHERE clause of the DELETE or the UPDATE statement instead of the WHERE CURRENT OF clause as shown in the below listing. For complete notes on programming in PL/SQL, we recommend the book Advanced PL/SQL: The Definitive Reference by Boobal Ganesan.
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The second way is a simple FOR – IN LOOP with the insert of the cursor variables.