15.1.9.3 ALTER TABLE Examples Begin with a table t1 created as shown here: CREATE TABLE t1 (a INTEGER, b CHAR(10)); 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 ...
ALTER TABLE t2 ADD INDEX (d), ADD UNIQUE (a); To remove column c: ALTER TABLE t2 DROP COLUMN c; To add a new AUTO_INCREMENT integer column named c: ALTER TABLE t2 ADD c INT UNSIGNED NOT NULL AUTO_INCREMENT, ADD PRIMARY KEY (c); ...
https://dev.mysql.com/doc/refman/8.0/en/alter-table-examples.html
Examples 1. Adding a Column ALTERTABLEemployeesADDCOLUMNbirthdateDATE; This example adds a new column `birthdate` of type `DATE` to the `employees` table. 2. Modifying a Column ALTERTABLEproductsMODIFYCOLUMNpriceDECIMAL(10,2); Here, the `price` column in the `products` table is modified to...
14.1.8.4 ALTER TABLE Examples 14.1.9 ALTER TABLESPACE Syntax ALTER TABLESPACEis useful only with Disk Data storage for MySQL Cluster. 14.1.10 ALTER VIEW Syntax userview_name column_list select_statement 14.1.11 CREATE DATABASE Syntax db_name ...
An action can be anything such as adding a new column, adding primary key, renaming table, etc. The ALTER TABLE statement allows you to apply multiple actions in a single ALTER TABLE statement, each action is separated by a comma (,).Let’s create a new table for practicing the ALTER ...
Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples: CREATE - to create objects in the database ALTER - alters the structure of the database DROP - delete objects from the database ...
altertable test add column dTime datetimegenerated always as (IFNULL(IFNULL(aTime, bTime), cTime)); 如此一来,每次新增或更新数据的时候,dTime都会自动计算,检索的时候,直接用这个字段就可以了,而且能为这个字段创建索引了,就将这个字段当做一个普通的字段,...
alter table college_pitcher_logs rename index game_date to idx_04; COMMIT; Issue #6: Missing data detected in tables resulting in Foreign Key Constraint failures Two values in table “pro_scouting_reports” were seen to be missing, thus preventing the creation of a number of Foreign Key cons...
mysql> ALTER TABLE test CHANGE name_varchar name_varchar VARCHAR(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci; Query OK, 0 rows affected (0.05 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> show full columns from test; ...