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To change column data type there are change method and modify method. ALTER TABLE student_info CHANGE roll_no roll_no VARCHAR(255); ALTER TABLE student_info MODIFY roll_no VARCHAR(255); To change the field name also use the change method. ALTER TABLE student_info CHANGE roll_no identity_no VARCHAR(255);
25 lis 2016 · Yes, you can use the ALTER TABLE t AUTO_INCREMENT = 42 statement. However, you need to be aware that this will cause the rebuilding of your entire table, at least with InnoDB and certain MySQL versions. If you have an already existing dataset with millions of rows, it could take a very long time to complete.
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.
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.
To rename the table from t1 to t2: ALTER TABLE t1 RENAME t2; To change column a from INTEGER to TINYINT NOT NULL (leaving the name the same), and to change column b from CHAR(10) to CHAR(20) as well as renaming it from b to c: ALTER TABLE t2 MODIFY a TINYINT NOT NULL, CHANGE b c CHAR(20);
You will learn how to use the MySQL ALTER TABLE statement to add a column, alter a column, rename a column, drop a column and rename a table.
The data type is a guideline for SQL to understand what type of data is expected inside of each column, and it also identifies how SQL will interact with the stored data. In MySQL there are three main data types: string, numeric, and date and time.
