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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. ON Persons (LastName); If you want to create an index on a combination of columns, you can list the column names within the parentheses, separated by commas: CREATE INDEX idx_pname.
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:
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;
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.
27 cze 2024 · The MySQL CREATE INDEX statement is a DDL (Data Definition Language) statement used to create indexes on tables. It allows developers to optimize query performance by specifying which columns should be indexed.
4 sty 2023 · CREATE INDEX names ON employees (last_name, first_name); In this case, the CREATE INDEX statement differs slightly. Now in the parentheses after the table name (employees), two columns are listed: last_name and then first_name. This creates a multi-column index on both columns.
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.
