Alter Table Modify Column Oracle Datatype

When modifying a tables column datatype you may want to export the rows redefine the table and then re import you data.

Alter table modify column oracle datatype. The alter table statement is used to add delete or modify columns in an existing table. Alter table customers modify customer name varchar2 100 not null. First you specify the name of the table which you want to add the new column after the alter table clause. 3 drop the old table column.

In a traditional database you would need to follow these cumbersome steps to alter a column data type. The statement is straightforward. Alter table table name modify column name action. Here are some examples of oracle alter table syntax to modify data columns and note that you can add constraints.

1 create the new column at the end of the table. Additional prerequisites for flashback data archive operations. To modify a column of a table you need to specify the column name table name and action that you want to perform. Alter table table name modify column name datatype.

Oracle provides alter table syntax to modify data columns in place in this form. To modify a column in an existing table the oracle alter table syntax is. Trying to do so will cause an error. Note that you cannot add a column that already exists in the table.

To use an object type in a column definition when modifying a table either that object must belong to the same schema as the table being altered or you must have either the executeanytypesystem privilege or the executeobject privilege for the object type. Second you specify the column name data type and its constraint. Let s look at an example that shows how to modify a column in an oracle table using the alter table statement. Alter table in oracle to change data type add a new column drop a column rename a column set a column unused and drop the unused column add modify or drop integrity constraints associated with the table or you can enable disable the constraints also.

2 run an update to populate the new table column. The alter table statement is also used to add and drop various constraints on an existing table. Alter table table name modify column name column type. If you are brave you can use a single alter table syntax to modify multiple columns.

4 re name the new column to the original column name. Alter table add column to add a column in a table use the following syntax.