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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).
There are cases where you can create a unique index that you cannot create a unique constraint. A function-based index, for example, that enforces conditional uniqueness. If I wanted to create a table that supported logical deletes but ensure that COL1 is unique for all non-deleted rows
The mapping between Python and Oracle objects is handled in SDOInConverter which uses the python-oracledb newobject() and extend() methods to create an Oracle object from the Python object values.
To create a unique index, you use the CREATE UNIQUE INDEX statement: CREATE UNIQUE INDEX index_name ON table_name(column1[,column2,...]); Code language: SQL (Structured Query Language) ( sql )
12 lut 2024 · In this example, we show how to create, view, and delete an index called idx_stud_ID on Stud_ID column in the “ Students ” table of a database. The following PL/SQL queries show how to improve database performance by index management, and provide insight into how indexing works in Oracle Database.
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.
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.
