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SQLALTER TABLEDDLtutorial

What is ALTER TABLE in SQL? Changing table structure for beginners

ALTER TABLE is the SQL command for "change the structure of an existing table". Plain words: add a column, drop, rename, change a type, add and drop constraints. Plus the main pain on production — long table locks and the add → backfill → drop pattern for safe migrations.

1 min readSQL · ALTER TABLE · DDL · tutorial

ALTER TABLE is the command for changing the structure of an existing table. Not the data inside (that's UPDATE), but the columns and rules themselves.

This article is currently in Russian. The full English translation is on the way.

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