mysql - Alter table on live production databases - Database Administrators Stack Exchange
The following approach has low risk, because the change is done in several low-risk steps that are very easy to roll back: Make sure that all the modules accessing the table are well covered with automated tests. However, this lock can be quite brief if the table doesn't require re-writing, no new UNIQUE, CHECK or FOREIGN KEY constraints need expensive full-table scans to verify, etc
13.1.4 ALTER TABLE Syntax
Updates and writes to the table that begin after the ALTER TABLE operation begins are stalled until the new table is ready, then are automatically redirected to the new table without any failed updates. If you use any option to ALTER TABLE other than RENAME, MySQL always creates a temporary table, even if the data wouldn't strictly need to be copied (such as when you change the name of a column)
To add a column called email to the contacts table created in Create a basic MySQL table with a datatype of VARCHAR(80), use the following SQL statement: ALTER TABLE contacts ADD email VARCHAR(60); This first statement will add the email column to the end of the table. it was of great help Randy It would be helpful to show an MYSQL example along with the SQL example Karan Sachdeva86 thank you Anonymous Thank you for this
Test Convert the ColumnsYou should test all of the changes before committing them to your database.The first thing to test is that the SQL generated from the conversion script is correct. But for column definitions that have specified lengths, defaults or NOT NULL:MyColumn VARCHAR(255) DEFAULT '' NOT NULLWe need to MODIFY keeping the same attributes, or the column definition will be fundamentally changed (see notes in ALTER TABLE)
mysql - How do I Alter Table Column datatype on more than 1 column? - Stack Overflow
Based on that, your ALTER command should be: ALTER TABLE webstore.Store MODIFY COLUMN ShortName VARCHAR(100), MODIFY COLUMN UrlShort VARCHAR(100) Note that: There are no second brackets around the MODIFY statements
You can also run these commands through a GUI or web interface, like the PHPMySqlAdmin tool.) Other MySQL ALTER TABLE ADD COLUMN examples Before I go back to work, here are some other MySQL ALTER TABLE ADD COLUMN examples, showing different approaches
MySQL :: MySQL 5.0 Reference Manual :: 13.1.4 ALTER TABLE Syntax
Updates and writes to the table that begin after the ALTER TABLE operation begins are stalled until the new table is ready, then are automatically redirected to the new table without any failed updates. If you use any option to ALTER TABLE other than RENAME, MySQL always creates a temporary table, even if the data wouldn't strictly need to be copied (such as when you change the name of a column)
MySQL :: MySQL 5.1 Reference Manual :: 13.1.7 ALTER TABLE Syntax
Updates and writes to the table that begin after the ALTER TABLE operation begins are stalled until the new table is ready, then are automatically redirected to the new table without any failed updates. For example, adding a member to a SET column that has 8 members changes the required storage per value from 1 byte to 2 bytes; this will require a table copy
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