Syntax ALTER TABLE `db_name`.`table_name` RT_ENGINE='COLUMNSTORE | ROWSTORE' īUILD TABLE `db_name`.RENAME TABLE order_auto_opt_v1 to order Ĭhange the storage model of the real-time storage engine for a table Execute the RENAME TABLE to statement to change the name of the temporary table to the name of the source table.RENAME TABLE order to order_backup -After data is imported, rename the source table as a backup. Execute the RENAME TABLE to statement to change the name of the source table.For more information, see Diagnostics on distribution field skew.
After data is imported, check for issues related to the new distribution key, such as data skew.For more information, see INSERT OVERWRITE INTO SELECT. Execute the INSERT OVERWRITE INTO SELECT statement to import data from the source table to the temporary table.PARTITION BY VALUE(DATE_FORMAT(order_time, '%Y%m%d')) LIFECYCLE 90 -Retain list partition settings. PRIMARY KEY (order_id,customer_id,order_time) -Add the distribution key customer_id and the partition key order_time to the primary key.ĭISTRIBUTED BY HASH(customer_id) -Change the distribution key from order_id to customer_id. Order_time timestamp NOT NULL COMMENT 'Order time', Order_id bigint NOT NULL COMMENT 'Order ID',Ĭustomer_id bigint NOT NULL COMMENT 'Customer ID',Ĭustomer_name varchar NOT NULL COMMENT 'Customer name', Create a temporary table named order_auto_opt_v1 by using the distribution key customer_id. In order to actually make use of the ALTER TABLE statement, run a query that changes the structure of a table ALTER TABLE is used to add, delete or modify columns in a table: the query can also be used to add indexes to columns.Its distribution key is intended to be changed from order_id to customer_id. In this example, a table named order is used. If you want to use a different partition or distribution key for your table, perform the following steps. Example ALTER TABLE adb_demo.customer TRUNCATE PARTITION ALL ĪnalyticDB for MySQL does not allow you to change or add partition or distribution keys.Syntax ALTER TABLE db_name.table_name MODIFY column_name data_type.ALTER TABLE adb_demo.customer MODIFY COLUMN province varchar comment 'The province where the customer is located' Ĭhange the value constraint for a column from NOT NULL to NULL Syntax ALTER TABLE db_name.table_name MODIFY column_name data_type comment 'new_comment' Ĭhange the comment of the province column in the customer table to "The province where the customer is located".ALTER TABLE adb_demo.customer DROP COLUMN province Remove the province column from the customer table. Syntax ALTER TABLE db_name.table_name DROP column_name data_type.ALTER TABLE adb_demo.customer ADD COLUMN province varchar comment 'Province' Syntax ALTER TABLE db_name.table_name ADD column_name data_type Īdd the province column of the VARCHAR data type to the customer table.You can use them to customize your database schema as per your requirement.Important The order of columns cannot be modified.
MYSQL ALTER TABLE ADD COLUMN HOW TO
In this article, we have learnt how to add one or more columns after a specific column in MySQL.
In both cases, the end result is the same. First product column is added after created_at, then modified_at is added, then quantity is added. ALTER TABLE salesĪDD COLUMN `product` varchar(6) AFTER `created_at` īut please note, in this case, the last ADD COLUMN statement should mention the first column that you want to be added. You can also use a single AFTER statement after the last ADD COLUMN command. In this case, MySQL will first add product column after created_at, modified_at column after created_at, and quantity column after modified_at. ALTER TABLE salesĪDD COLUMN `modified_at` date AFTER `product`,ĪDD COLUMN `quantity` int AFTER `modified_at` Let us say you want to add multiple columns product, modified at, quantity after created_at, then here is how to do it using multiple ADD COLUMN commands, each followed by AFTER clause. mysql> ALTER TABLE salesĪDD COLUMN `product` varchar(6) AFTER `created_at`, Then we need to mention AFTER clause and then the column name after which you want to add the new column. We need to specify the new column name after ADD COLUMN, followed by its definition. In the above command, we use ALTER TABLE command to add column, followed by ADD COLUMN command. alter table table_nameĪdd column column_name1 column_definition AFTER column_name2 Let us say you want to add another column product after created_at column. mysql> create table sales(id int, created_at date, amount int) Let us say you have the following MySQL table sales(id, created_at, amount). How to Add Column After Another Column in MySQL In this article, we will learn how to add column after another column in MySQL. But sometimes, you may need to add one or more columns after another column in MySQL.
Generally, database developers add one or more columns anywhere in a MySQL table without preferences.
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