![]() Alter drop column in table Syntax ALTER TABLE table_name DROP existing_column_name 2.1 Alter drop column in table command ALTER TABLE student DROP age Alter drop column in table 2. Add column in table Syntax ALTER TABLE table_name ADD new_column_name column_definition 1.1 Add column in table command ALTER TABLE student ADD age int(2) Add column in table command 1.2 Alter add column at first ALTER TABLE student ADD age int(2) FIRST Alter add column at first 1.3 Alter add column after column ALTER TABLE student ADD telephone_number VARCHAR(20) AFTER name Alter add column after column alter table add column MySQL 1.4 Alter add multiple columns after column or default ALTER TABLE student ADD username VARCHAR(255),add password VARCHAR(255) AFTER mobile Alter add multiple columns after column or default 1.5 Modify Auto Increment Value ALTER TABLE student AUTO_INCREMENT = 1000 Modify Auto Increment Value 1.6 MySQL alter table modify column ALTER TABLE student MODIFY address VARCHAR(500) Modify varchar() datatype. 1.4 Alter add multiple columns after column or defaultġ.The ALTER statement is always used with “ ADD“, “ DROP” and “ MODIFY” commands according to the situation. It is also used to add or delete an existing column in a table. Or you can used when you want to change the name of your table or any table field. Syntax ALTER TABLE `db_name`.`table_name` RT_ENGINE='COLUMNSTORE | ROWSTORE' īUILD TABLE `db_name`.MySQL alter command is used to modify an existing database, table, view or other database objects that might need to change during the life cycle of a database.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. The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. 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. To add a column to the index, use ALTER TABLE tablename ADD INDEX indexname. Order_time timestamp NOT NULL COMMENT 'Order time', Index is used to query the results from MySQL Table with improved performance. Idal pour ajouter une colonne, supprimer une colonne ou modifier une colonne. Order_id bigint NOT NULL COMMENT 'Order ID',Ĭustomer_id bigint NOT NULL COMMENT 'Customer ID',Ĭustomer_name varchar NOT NULL COMMENT 'Customer name', La commande ALTER TABLE en SQL permet de modifier une table existante. Create a temporary table named order_auto_opt_v1 by using the distribution key customer_id.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".Parameters: oldname: It is used to specify the. ALTER TABLE adb_demo.customer DROP COLUMN province Syntax: ALTER TABLE tablename CHANGE COLUMN oldname newname columndefinition FIRST AFTER columnname. Remove the province column from the customer table. ![]() To add multiple columns SQL, specify multiple columns to add after. Syntax ALTER TABLE db_name.table_name DROP column_name data_type In this situation, you can use the ALTER TABLE ADD statement to add multiple columns in SQL.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.Important The order of columns cannot be modified.
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