- Tags: Keyword, MySQL, SQL Server
- Categories: Reference, SQL Keywords, SQL Reference
Quick Reference
Indexes are used to speed up the retrieval of data (searches/queries) from the database.
CREATE INDEX
The following creates an index named “idx_last_name” on the last_name column in the Customers table.
CREATE INDEX idx_last_name
ON Customers (last_name);
The following creates an index named “idx_full_name” on the combination of the first_name and last_name columns in the Customers table.
CREATE INDEX idx_full_name
ON Customers (first_name, last_name);
CREATE UNIQUE INDEX
The following creates a unique index named “uidx_customer” on the “id_customer” column in the Customers table.
CREATE UNIQUE INDEX uidx_customer
ON Customers (id_customer);
DROP INDEX
The following deletes an index named “idx_customer” from the Customers table.
MySQL:
ALTER TABLE Customers
DROP INDEX idx_customer;
SQL Server:
DROP INDEX Customers.idx_customer;
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SQL NOTES:
- Any work being done to modify the structure of a database or delete tables or the the database itself should only be done after making a recent backup
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