Αποτελέσματα Αναζήτησης
If you want to update specific rows (ie where the IDs match) you probably want to do a coordinated subquery. However, since you are using Oracle, it might be easier to create a materialized view for your query table and let Oracle's transaction mechanism handle the details.
6 Δεκ 2017 · Learn about several methods to update data using subqueries in UPDATE statements to make them more effective and easier to maintain in Oracle SQL.
Subquery Method. The first option is to do an update of the DEST_TAB table using a subquery to pull the correct data from the SOURCE_TAB table. Notice the EXISTS predicate to exclude rows from the DEST_TAB table with no matching row in the SOURCE_TAB table.
Take a look at the following diagram below for the syntax and an example of updating records within object tables: The UPDATE statement specifying the table; SET attribute name equal to sub query; From table name; where clause for the sub query to retrieve the reference information; WHERE clause for the update statement
Introduction to the Oracle subquery. A subquery is a SELECT statement nested inside another statement such as SELECT, INSERT, UPDATE, or DELETE. Typically, you can use a subquery anywhere that you use an expression. Consider this following subquery example that uses the products table from the sample database.
This statement uses a correlated subquery to update a single column across multiple rows in the FLIGHTS table. It increases the duration of all BA flights by thirty minutes. The subquery returns all flights with OPERATING_CARRIER_CODE set to 'BA'.
23 Αυγ 2016 · I have a table with 18 million rows. I need to do an once-off update to fix a data issue. CREATE TABLE TESTLARGE (CODE number, STATE varchar2 (5), SDATE date, flag char (1)); I have to update the FLAG='Y' based on state and date. UPDATE TESTLARGE SET FLAG='Y' WHERE CODE IN (SELECT CODE FROM TESTLARGE where STATE in ('PRE', 'POST', 'START', 'END
