In this image, we can see that the data type of column name account_num is int.
In that case, we first check the structure of the table using the DESCRIBE statement as follows: Suppose we have a table named balance that contains the data as follows:ĭue to some reason, we need to change the column name account_num along with its data type. Let us understand how the CHANGE statement works in MySQL to rename a column through the various examples.
All information of column attributes might not be available to the application for renaming. Answer (1 of 3): By using the ALTER table syntax.But, sometimes the CHANGE statement might have the following disadvantages:
#MYSQL RENAME COLUMN HOW TO#
This syntax can also allow us to change the column's data types. How to rename a column in MySQL CREATE studentid VARCHAR enrolldate DATE SELECT. In this syntax, we can see that we may require re-specification of all the column attributes. TABLES=mysql -user=$2 -password=$3 -h $1 -e "select TABLE_NAME from information_schema.CHANGE COLUMN old_column_name new_column_name Data Type # Copyright 2013 Percona LLC and/or its affiliatesĭb_exists=`mysql -h $1 -e "show databases like '$3'" -sss`Įcho "ERROR: New database already exists $3"Ĭharacter_set=`mysql -h $1 -e "show create database $2G" -sss | grep ^Create | awk -F'CHARACTER SET ' '' 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 column b from CHAR (10) to CHAR (20) as well as renaming it from b to c. Once triggers are dumped, we will need to drop them from the schema, for RENAME TABLE command to work. Because business requirements change, we need to rename the current table to a new one to better reflect the new situation. This is done using -E, -R flags (in addition to -t -d which dumps the triggers) to the mysqldump command. To remedy this we can do the following things :ġ) Dump the triggers, events and stored routines in a separate file. For more information on how to rename a column, check it out the renaming column tutorial. MySQL’s “RENAME TABLE” fails if there are triggers exists on the tables. ALTER TABLE tablename RENAME COLUMN currentname TO newname. If there are views, triggers, functions, stored procedures in the schema, those will need to be recreated too. b) Rename the tables from old schema to the new schema, using MySQL’s “RENAME TABLE” command.The ALTER TABLE statement is also used to add and drop various constraints on an existing table. a) Create the new database schema with the desired name. MySQL ALTER TABLE Statement The ALTER TABLE statement is used to add, delete, or modify columns in an existing table.Here is the procedural approach at doing the rename: This takes a short time to complete since changing a table’s name or its schema is only a metadata change. This rename operation is atomic and no one else can access the table while it is being renamed. Method 2: MySQL has a very good feature for renaming tables that even works across different schemas. To remedy such situations, there is another quick method to rename schemas, however, some care must be taken while doing it. What if the schema is more than a 100GB? There are methods where you can pipe the above commands together to save on space, however, it will not save time. # mysql -e "DROP DATABASE emp "Īlthough the above method is easy, it is time and space consuming.
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