从 oracle-sql 中的特定列中删除整个数据
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Deleting entire data from a particular column in oracle-sql
提问by RajeeV VenkaT
Recently I have started learning Oracle-sql. I know that with the help of DELETEcommand we can delete a particular row(s). So, Is it possible to delete entire data from a particular column in a table using only DELETEcommand. (I know that using UPDATEcommand by setting null values to entire column we can achieve the functionality of DELETE).
最近我开始学习了Oracle-sql。我知道在DELETE命令的帮助下我们可以删除特定的行。那么，是否可以仅使用DELETE命令从表中的特定列中删除整个数据。（我知道UPDATE通过将空值设置为整个列来使用命令，我们可以实现 的功能DELETE）。
回答by Lukasz Szozda
The DELETE statement removes entire rowsof data from a specified table or view
DELETE 语句从指定的表或视图中删除整行数据
If you want to "remove" data from particular column update it:
如果要从特定列中“删除”数据，请更新它：
UPDATE table_name
SET your_column_name = NULL;
or if column is NOT NULL
或者如果列是 NOT NULL
UPDATE table_name
SET your_column_name = <value_indicating_removed_data>;
You can also remove entire column using DDL:
您还可以使用 DDL 删除整个列：
ALTER TABLE table_name DROP COLUMN column_name;
回答by mAEHS
Use Invisible Type, which is from an oracle 12cR2.
使用来自oracle 12cR2 的Invisible Type 。
ALTER TABLE LOG1
MODIFY operation INVISIBLE
It is a better than drop of a particular column.If you need to visible you can get back by altering with an VISIBLEof a column name.
这比删除特定列要好。如果您需要可见，您可以通过更改VISIBLE列名来返回。
回答by Gordon Linoff
In SQL, deletedeletes rows not columns.
在 SQL 中，delete删除的是行而不是列。
You have three options in Oracle:
在 Oracle 中有三个选项：
- Set all the values to
NULLusing update. - Remove the column from the table.
- Set the column to unused.
- 将所有值设置为
NULL使用更新。 - 从表中删除该列。
- 将列设置为未使用。
The last two use alter table:
最后两个使用alter table：
alter table t drop column col;
alter table t set unused (col);
回答by malik Shaikh
update employee set commission=nvl2(commission,'','')
update employee set commission=nvl2(commission,'','')
this will remove all the data from the column
这将从列中删除所有数据
