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CREATE UNIQUE INDEX Syntax. Creates a unique index on a table. Duplicate values are not allowed: CREATE UNIQUE INDEX index_name. ON table_name (column1, column2, ...); MySQL CREATE INDEX Example. The SQL statement below creates an index named "idx_lastname" on the "LastName" column in the "Persons" table: CREATE INDEX idx_lastname.
CREATE INDEX enables you to add indexes to existing tables. CREATE INDEX is mapped to an ALTER TABLE statement to create indexes. See Section 15.1.9, “ALTER TABLE Statement”. CREATE INDEX cannot be used to create a PRIMARY KEY; use ALTER TABLE instead.
To create an index for a column or a list of columns, you specify the index name, the table to which the index belongs, and the column list. For example, to add a new index for the column c4, you use the following statement: CREATE INDEX idx_c4 ON t(c4); Code language: SQL (Structured Query Language) (sql)
27 cze 2024 · The syntax for adding an index is: CREATE INDEX index_name. ON table_name (column_names); index_name: The name of the index. table_name: The name of the table to which the index belongs. column_names: The list of columns to be indexed. Example: Adding an Index to a Column.
Creating indexes – introduce the index concept and show you how to create an index for one or more columns of a table. Removing indexes – show you how to remove an existing index of a table. Listing table indexes – provide you with a statement to list all indexes or specific indexes of a table.
You can use this syntax to add an index and control the kind of index (HASH or BTREE). create index your_index_name on your_table_name(your_column_name) using HASH; or. create index your_index_name on your_table_name(your_column_name) using BTREE;
The basic syntax for the CREATE INDEX statement is as follows: CREATE [UNIQUE | FULLTEXT | SPATIAL] INDEX index_name USING [BTREE | HASH | RTREE | ...] ON table_name (column_name [(length)] [ASC | DESC],...);
