How would you delete old data from a database schema so that it retains only the current year’s rows in all the tables in the schema, and the rest of the data is erased?
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CTAS
In a perfect world, the database design would be firm and final before development starts. But we do not live in a perfect world – changes can and do happen. You forgot a column in a table, or your client has a change request – for various reasons, you may find that you need to add a column to an existing table.
Oracle allows you to alter a table easily for adding a column, but what if you want the new column added at a specific position in the table? Now you’re in a spot. There is no command to “alter table add column at position 2”; Oracle simply places the column after all the existing columns.
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You have probably heard other DBAs/developers and websites talk about creating a database table through CTAS. Does that term leave you befuddled? There’s a very simple explanation to that acronym – read on!
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