91 lines
2.9 KiB
MySQL
91 lines
2.9 KiB
MySQL
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-- +----------------------------------------------------------------------------+
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-- | Jeffrey M. Hunter |
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-- | jhunter@idevelopment.info |
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-- | www.idevelopment.info |
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-- |----------------------------------------------------------------------------|
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-- | Copyright (c) 1998-2012 Jeffrey M. Hunter. All rights reserved. |
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-- |----------------------------------------------------------------------------|
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-- | DATABASE : Oracle |
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-- | FILE : example_drop_unused_column.sql |
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-- | CLASS : Examples |
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-- | PURPOSE : Example SQL syntax used to drop unused columns from a table. |
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-- | NOTE : As with any code, ensure to test this script in a development |
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-- | environment before attempting to run it in production. |
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-- +----------------------------------------------------------------------------+
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connect scott/tiger
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set serveroutput on
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Prompt ======================
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Prompt DROP existing table...
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Prompt ======================
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Prompt
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accept a1 Prompt "Hit <ENTER> to continue";
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DROP TABLE d_table
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/
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Prompt =======================
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Prompt CREATE TESTING TABLE...
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Prompt =======================
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Prompt
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accept a1 Prompt "Hit <ENTER> to continue";
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CREATE TABLE d_table (
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id_no NUMBER
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, name VARCHAR2(100)
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, d_column VARCHAR2(100)
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)
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/
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Prompt ========================
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Prompt MARK COLUMN AS UNUSED...
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Prompt ========================
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Prompt
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accept a1 Prompt "Hit <ENTER> to continue";
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ALTER TABLE d_table SET UNUSED COLUMN d_column;
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Prompt =======================================
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Prompt QUERY ALL TABLES WITH UNUSED COLUMNS...
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Prompt =======================================
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Prompt
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accept a1 Prompt "Hit <ENTER> to continue";
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SELECT * FROM sys.dba_unused_col_tabs;
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Prompt ======================================
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Prompt PHYSICALLY REMOVE THE UNUSED COLUMN...
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Prompt ======================================
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Prompt
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accept a1 Prompt "Hit <ENTER> to continue";
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ALTER TABLE d_table DROP UNUSED COLUMNS;
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Prompt ================================================
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Prompt IF YOU WANTED TO PHYSICALLY REMOVE THE COLUMN...
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Prompt ================================================
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Prompt
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accept a1 Prompt "Hit <ENTER> to continue";
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-- ALTER TABLE d_table DROP COLUMN d_column;
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Prompt =========================================
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Prompt OPTIONALLY SYNTAX FOR REMOVING COLUMNS...
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Prompt =========================================
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Prompt
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Prompt ALTER TABLE d_table DROP COLUMN d_column CASCADE CONSTRAINTS;
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Prompt ALTER TABLE d_table DROP COLUMN d_column INVALIDATE;
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Prompt ALTER TABLE d_table DROP COLUMN d_column CHECKPOINT 1000;
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Prompt
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accept a1 Prompt "Hit <ENTER> to EXIT";
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