Column

How to Resolve ORA-01439: column to be modified must be empty to change datatype

by Ed Chen
June 9, 2021June 17, 2021

ORA-01439 ORA-01439 means that the data type of a column you want to change is not empty, you have to make it empty first, then… Read More »

How to Re-Order Column Position of a Table

by Ed Chen
May 12, 2021April 11, 2021

One developer reported that some statements like the following failed to complete. SQL> insert into finapp.invoices_history select * from finapp.invoices_month where invoice_date < sysdate -30;… Read More »

How to Modify VARCHAR2 to CLOB of a Column

by Ed Chen
February 24, 2021March 14, 2021

Major Data Types There're several major data types built in Oracle. Character Numeric Datetime LONG RAW LOB (Large Object) In each major data types, minor… Read More »

How to Resolve ORA-00932: inconsistent datatypes: expected CHAR got LONG

by Ed Chen
November 28, 2020April 20, 2021

ORA-00932 ORA-00932 means that SQL engine wanted to retrieve CHAR strings, but it saw LONG data type, which is unsearchable. So SQL engine refused to… Read More »

ORA-12991: column is referenced in a multi-column constraint

by Ed Chen
April 25, 2020May 6, 2020

ORA-12991 ORA-12991 means that the column you want to drop is bound to some multi-column constraint. Usually, it's a primary key constraint, but not always.… Read More »

How to Resolve ORA-01442: column to be modified to NOT NULL is already NOT NULL

by Ed Chen
December 25, 2019March 23, 2021

ORA-01442 ORA-01442 means that the target column is already NOT NULL, you don't have to add it again by modifying the column. I know sometimes… Read More »

How to Add or Drop NOT NULL Constraint

by Ed Chen
November 23, 2019January 20, 2021

A. Add NOT NULL Constraint As I mentioned in How to Resolve ORA-00904 for ALTER TABLE ADD CONSTRAINT, NOT NULL is a constraint, but it's… Read More »

How to Resolve ORA-12899: value too large for column

by Ed Chen
November 13, 2019November 13, 2019

ORA-12899 ORA-12899 means that the value of being inserted or updated data is larger than column's allowable length that is defined in the table. Let's… Read More »