Oracle update SQL Tips

Question:  What is the syntax for an Oracle update statement?

Answer:  The Oracle update SQL syntax is too% ANSI compliant, and the Oracle documentation provides examples of the SQL update statement syntax. 

The Oracle UPDATE statement locates one or more rows (or all the rows) in a table and sets one or more columns to the specified values. As with the INSERT statement, the values must either match the columns data type or one that the database can implicitly convert. The basic format is:

update <table name> set (<col1 = val1, col2 = val2,col3 = val3,?) where <expression identifying rows to change>;

Let's go back to the AUTHOR table and look at some examples of Oracle updates. As with the INSERT section, I rolled back the changes to the original table.

To set each author contract number to zero, simply leave off the WHERE clause. If you do not specify a row, then all rows are updated when Oracle update is used.

SQL> select author_key, author_contract_nbr from author;

AUTHOR_KEY AUTHOR_CONTRACT_NBR
----------- -------------------
A101 5601
A102 5602
A103 5603
A104 6602
A105 7896
A106 6547
A107 3452
A108 7954
A109 1
A110 2853

10 rows selected.

SQL> update author set author_contract_nbr = 0000;

10 rows updated.

The command returns the table to the state it was in before the Oracle updates.

To change the contract number for author A109 to 999, use the statement below. Notice that the WHERE clause identifies which row will be updated with Oracle UPDATE SQL.

SQL> update
2 author
3 set author_contract_nbr = 999
4 where
5 author_key = 'A109';

1 row updated.

I can also update multiple columns in one Oracle update. A comma separates each column to be updated. All of the columns identified will be changed for all the rows specified in the WHERE clause.

SQL> update
2 author
3 set author_contract_nbr = 8888,
4 author_zip = 32076
5 where
6 author_state = 'MO';

3 rows updated.

One of the powerful features of the Oracle update statement is the ability to update rows using a query.

update <table name> set (col1, col2, col3,?) = (<query>)
where <expression>;

The query must have a value in the select clause for each column in the column list. If the where clause is not used all rows are updated when the Oracle update is executed.

SQL> update
2 sales
3 set (order_date, quantity) = (select
4 SYSDATE,
5 avg(quantity)
6 from sales
7 where book_key = 'B102'
8 group by book_key, SYSDATE)
9 where book_key = 'B102';

11 rows updated.

Here are my other notes on Oracle update statement syntax and usage:

• Oracle Update Statement

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