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Table Options. table_options signifies table options of the kind that can be used in the CREATE TABLE statement, such as ENGINE, AUTO_INCREMENT, AVG_ROW_LENGTH, MAX_ROWS, ROW_FORMAT, or TABLESPACE.. For descriptions of all table options, see Section 15.1.20, “CREATE TABLE Statement”.However, ALTER TABLE ignores DATA DIRECTORY and INDEX DIRECTORY when given as table options.
- MySQL :: MySQL 8.4 Reference Manual :: 15.1.15 CREATE INDEX Statement
CREATE INDEX enables you to add indexes to existing tables....
- MySQL :: MySQL 8.4 Reference Manual :: 15.1.15 CREATE INDEX Statement
Indexes of two types can be added: when you define a primary key, MySQL will take it as index by default. Explanation. Primary key as index. Consider you have a tbl_student table and you want student_id as primary key: ALTER TABLE `tbl_student` ADD PRIMARY KEY (`student_id`)
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.
The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. The ALTER TABLE statement is also used to add and drop various constraints on an existing table.
26 sty 2024 · Here’s the basic syntax: CREATE INDEX index_name ON table_name (column1, column2,...); For instance, to create a single-column index: CREATE INDEX idx_lastname ON users (lastname); And here’s how you might create a multi-column index: CREATE INDEX idx_name ON users (lastname, firstname);
In this article, we described how to use the ALTER TABLE statement modify a table, including: adding columns, deleting columns, modifying columns, renaming columns, renaming tables, setting primary keys, etc.
27 cze 2024 · The ALTER TABLE statement can be used to: Add, modify, or drop columns belonging to a certain table. Add, modify, or delete indexes from a table. Add, drop, discard, import, truncate, reorganize, repair, remove, or otherwise modify partitions.
