Can we ALTER TABLE?

Question

The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. The ALTER TABLE statement is also used to add and drop various constraints on an existing table.

Can we ALTER a table with data?

Existing tables can be altered with an ALTER TABLE statement. An ALTER TABLE statement is part of DDL, and is for altering a table schema only; we'll look at updating data in a table later in this book.

Can we ALTER TABLE name?

Sometimes we may want to rename our table to give it a more relevant name. For this purpose we can use ALTER TABLE to rename the name of table.

What are the restrictions on ALTER TABLE?

- Column can't be deleted with alter command. - Column can't be renamed a column. - Column can't be added in between of the existing columns.

Is ALTER TABLE blocking?

When you run an alter table statement, PostgreSQL will update the table structure and there is no locking unless you do something that needs to alter existing rows.

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