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The following example creates a unique index on the email column of the members table: CREATE UNIQUE INDEX members_email_i ON members(email); Code language: SQL (Structured Query Language) ( sql ) By having this members_email_i index, you cannot have two rows with the same value in the email column.
- Oracle Function-based Index
Summary: in this tutorial, you will learn how to use the...
- Oracle DROP INDEX
Oracle DROP INDEX statement example. The following statement...
- Create Index
By default, the CREATE INDEX statement creates a btree...
- Oracle Function-based Index
1 lis 2013 · When you specify a unique constraint on one or more columns, Oracle implicitly creates an index on the unique key. If you are defining uniqueness for purposes of query performance, then Oracle recommends that you instead create the unique index explicitly using a CREATE UNIQUE INDEX statement..... it is not accurate.
3 dni temu · A PL/SQL Unique Index is a powerful database object used to ensure the uniqueness of values in one or more columns of a table. In Oracle databases, indexes play an important role in enhancing query performance by enabling quick retrieval of rows.. The unique index specifically enforces a rule that no two rows in a table can have the same values for the indexed column(s).
Instead you have to create a function-based unique index. create unique index calendar_date_u on calendar_dates ( trunc ( calendar_date ) ) Index created.
CREATE UNIQUE INDEX fn_unique_idx ON table1 (CASE WHEN is_deleted='N' THEN id ELSE null END, CASE WHEN is_deleted='N' THEN name ELSE null END, CASE WHEN is_deleted='N' THEN type ELSE null END); An example of the constraint in action
5 paź 2024 · Use the CREATE UNIQUE INDEX statement to create a unique index. This statement creates a unique index. Alternatively, you can define UNIQUE integrity constraints on the desired columns. The database enforces UNIQUE integrity constraints by automatically defining a unique index on the unique key.
10 sie 2017 · When you create a primary key or unique constraint, Oracle Database will automatically create a unique index for you (assuming there isn't an index already available). In most cases you'll add the constraint to the table and let the database build the index for you.
