![]() UPDATE mytable SET `type` = CASE `type` WHEN '0' THEN 'Something' ELSE 'TEST' END Įither way, be sure to test this first on another table before trying it on your real table. ALTER TABLE mytable MODIFY COLUMN `type` VARCHAR(10) If the table has millions of rows, you may have to do this in batches.ĭrop the old column and optionally rename the new column to the name of the old one: ALTER TABLE mytable DROP COLUMN `type`, RENAME COLUMN type2 to `type` Īnother approach would be to change the column, allowing integers to convert to the string format of the integer values. That is, an integer will be translated to the string format of that integer value, just it would in a string expression.Īdd a new column: ALTER TABLE mytable ADD COLUMN type2 VARCHAR(10) īackfill that column: UPDATE mytable SET type2 = CASE `type` WHEN 0 THEN 'Something' ELSE 'TEST' END ![]() ALTER TABLE MyTable MODIFY COLUMN foo VARCHAR(32) NOT NULL. You can't rename a column using modify and other. By doing this you can allow more or less characters than before. First, create the new column with type data Next, run update query, to populate the new column with the value of the old one, applying any conversion if needed Next, drop the old column Finally, rename the new column to the old one. An ALTER TABLE in MySQL will only translate values using builtin type casting. Start with altering the default charset of new tables by changing the DB definition (like in all other answers): ALTER DATABASE databasename CHARACTER SET utf8mb4 COLLATE utf8mb4unicodeci Then generate sql to change the default charset for new columns of all existing tables: SELECT concat ('ALTER TABLE ',tableschema,'.',tablename. MODIFY COLUMN This command does everything CHANGE COLUMN can, but without renaming the column.You can use the modify SQL command if you need to resize a column in MySQL. There's no way to modify values during an ALTER TABLE. ![]() ![]() The syntax you show has no equivalent in MySQL. ![]()
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