Updating a table from another table in oracle
Cross table update (also known as correlated update, or multiple table update) in Oracle uses non-standard SQL syntax format (non ANSI standard) to update rows in another table. Update data in table A based on two or more common columns in table B.
The differences in syntax are quite dramatic compared to other database systems like MS SQL Server or My SQL. Updates based on two or more common columns are normally used for tables where multiple columns work together as a primary key (known as composite primary key).
I have one table A has column (id, field_1,field_2), and another table B has column (id,field_2) Now I want to merge table B to A, that means i want to update field_2 in table A to value of table B. BTW I am using oracle Thanks Now, each time the above is executed, it will do it across all rows in the table.
If this is something you need to do all the time, I would suggest something else, but for a one-off or very small tables it should be sufficient.
Should any right be infringed, it is totally unintentional.
Drop me an email and I will promptly and gladly rectify it.
Oracle lets you write stored procedures and anonymous PL/SQL blocks that use dynamic SQL. DEFINE_COLUMN(curid, i, numvar); ELSIF desctab(i).col_type = 12 THEN DBMS_SQL. COLUMN_VALUE(curid, i, namevar); ELSIF (desctab(i).col_type = 2) THEN DBMS_SQL. CLOSE_CURSOR(curid); END; / CREATE OR REPLACE PROCEDURE DO_QUERY(mgr_id NUMBER) IS TYPE Cur Type IS REF CURSOR; src_cur Cur Type; curid NUMBER; sql_stmt VARCHAR2(200); ret INTEGER; empnos DBMS_SQL.
Dynamic SQL statements are not embedded in your source program; rather, they are stored in character strings that are input to, or built by, the program at runtime. COLUMN_VALUE(curid, i, numvar); ELSIF (desctab(i).col_type = 12) THEN DBMS_SQL.
Preventing Malicious or Accidental Access of Open Cursor Numbers An error, subprogram is called with a cursor number that does not denote an open cursor. This index is initialized to "indx" at declare c NUMBER; d NUMBER; n_tab DBMS_SQL. Consequently, to prevent this, you might do this: One potential issue may arise when the subquery actually finds more than one matching row in tbl B.If this happens, the UPDATE will terminate with an error ("subquery may return only one row"). works fine when I try to update all the records in tbl A, however, in this case I only have missing data which I have identified and populated in tbl B.When I try to update only the missing data the non-matched data is also updated but to NULL. The reason some of your rows are getting NULLs updated is due to the subquery.