Selecting from and updating the same table oracle
will set the year to the current year, so every row will end up with the first of a month in 2016, regardless of the original hire year - which might not be desirable. This means that you have to select on all the fields which comprise a unique key -- a non-unique primary key is not sufficient.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).In this article, we are going to look at four scenarios for Oracle cross table update. Category_ID) where exists ( select * from Categories b where b. These columns uniquely identify a record in a table.T-SQL is designed to be set-based, so it works on entire sets of data as a whole; it should NOT be used to work on data line-by-line.
We are going to update column DESCRIPTION and PICTURE in table Categories_Test by using data in table Categories, based on data in the common column CATEGORY_ID. Update data in a column in table A based on a common column in table B. Update data in two columns in table A based on a common column in table B. Conditionally update data in table A based on a common column in table B. No portion may be reproduced without my written permission.
where (column1,column2) in ( I didn't down rate, but it isn't a good solution.
Firstly: if the subselect was returning multiple values, then the for loop will be overwriting the name on table2 multiple times for some/all records (not clean). Assuming the outcome of the for loop was intended, the original subselect could have been rewritten in some controlled way to return only 1 value for each record...
I have table hire_table containing 2 columns id , hire_date . Is there a way to extract the month number from the date and simultaneously update the hire_table ? 1) create a separate table to extract id and month number.
create table monthtable as( select id , EXTRACT(month FROM hire_date) as monthno from hire_table); 2)using left join combine the 2 tables.