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Editorial Team
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Asked: 2026-05-20T00:24:18+00:00

I have a table with 50+ columns and I need to swap the order

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I have a table with 50+ columns and I need to swap the order of the first two columns. What is the best way to accomplish this using Oracle? Assume the table name is ORDERDETAILS and as it is, the first two columns are ITEM_ID and ORDER_ID. Once the rename is complete, the table name should still be ORDERDETAILS but the first two columns will be ORDER_ID and ITEM_ID. FWIW, column types and the rest of the columns and their order is irelevent.

Correct me if I’m wrong, but I think the general steps are:

  1. Rename the existing table.
  2. Drop the primary key constraint.
  3. Re-create the table with the correct column order.
  4. List item
  5. Run INSERT INTO .. SELECT to move the data from temp to the table in step #3.
  6. Drop the temp table.

I have little experience with Oracle so perhaps I’m missing a step or two.

Does a primary key imply an index in Oracle? Does dropping the primary key also drop the index?

SQL examples are much appreciated.

EDIT: Un-sincere thanks to those who question why it needs done instead of providing help. To answer your question as to why it needs done: I’m following orders from someone else who says I need to do it this way and the order of the columns DOES matter. My thoughts/opinions on this are irrelevent.

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1 Answer

  1. Editorial Team

    Look at the package DBMS_Redefinition. It will rebuild the table with the new ordering. It can be done with the table online.

    As Phil Brown noted, think carefully before doing this. However there is overhead in scanning the row for columns and moving data on update. Column ordering rules I use (in no particular order):

    • Group related columns together.
    • Not NULL columns before null-able columns.
    • Frequently searched un-indexed columns first.
    • Rarely filled null-able columns last.
    • Static columns first.
    • Updateable varchar columns later.
    • Indexed columns after other searchable columns.

    These rules conflict and have not all been tested for performance on the latest release. Most have been tested in practice, but I didn’t document the results. Placement options target one of three conflicting goals: easy to understand column placement; fast data retrieval; and minimal data movement on updates.

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