#Alter table add column update#

Change Default Value Of ColumnĪLTER TABLE command can also be used to SET/Change the DEFAULT value for an existing column. Notice the name ‘address’. This should match the index name in the output of the SHOW CREATE TABLE command. The above command will DROP the FULLTEXT Index that we have added for the address field. Similar to Creating Indexes, the ALTER command can also be used to drop existing indexes from the table.Įxample: ALTER TABLE employee DROP INDEX address In the above output, you will observe that all the indexes have been created as per the value in the create_table column. ALTER TABLE employee ADD FULLTEXT(address) įor all the above 4 examples, we can run the SHOW CREATE TABLE command to get the details about the indexes created. We will be adding a FULLTEXT Index on the ‘name’ column values in the Employee table. #4) Add FULLTEXT Index: This is a special type of Index which is used for text searching purposes.

#3) Add INDEX: Add an ordinary index against any column.Īdd a normal index on the ‘address’ field in the Employee table. Add a UNIQUE index on the ‘name’ column in the Employee table as shown below. Suppose hypothetically we just want unique names in a table. #2) Add UNIQUE: Adds or creates Unique index against given column(s) ALTER TABLE employee ADD PRIMARY KEY (id) In the below example, use the Employee table and add the PRIMARY KEY Index to the ‘Id’ column. #1) Add PRIMARY KEY: This command adds a PRIMARY KEY index against a given column (or columns) There can be four different types of indexes that can be added using the ALTER TABLE command. MySQL ALTER table command also allows you to create or drop INDEXES against a table. ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci To validate if the ALTER command succeeded, you can run the SHOW COLUMNS command. Please note that, while dropping a COLUMN, you just need to mention the column name and not its data type. ALTER TABLE employee DROP COLUMN department_id Try to remove the above-added column department_id from the Employee table.

Similar to adding a new column, the MySQL ALTER command can be used to drop an existing column from the table. ALTER TABLE employee ADD COLUMN department_id INT DROP COLUMN With the above sample tables, let’s add a new column named ‘department_id’ of type INT in the table Employee. Let’s look at different scenarios with the help of examples.

#Alter table add column update#

The MySQL ALTER Command can be used for multiple things like add/drop a column, add/drop index or constraint, and update a table itself. Box 625, 5744 Proin Avenue') ĭifferent Ways To Use ALTER Table Command INSERT INTO `employee` (`id`,`name`,`address`) VALUES (1,'Alyssa INSERT INTO `employee_department`(`name`,`id`) VALUES ('Information CREATE TABLE IF NOT EXISTS Employee_Department ( We will learn to add them using the ALTER command in the examples shown in the below sections as we discuss. We haven’t added any FOREIGN KEY constraints among these tables. We are also adding some dummy data to both the tables.

Let’s look at different majorly used alter_options provided by MySQL.įor the purpose of understanding different usages of the ALTER command, we will use 2 sample tables – Employee and Department having the structure as mentioned below. Here table_name is the name of the table on which we want to perform the alter action. One or more alter_options can be specified along with the ALTER TABLE command. Different Ways To Use ALTER Table Command.