DROP COLUMNS

Function

This command is used to delete one or more columns from a table.

Syntax

ALTER TABLE [db_name.]table_name DROP COLUMNS (col_name, ...);

Parameter Description

**Table 1** DROP COLUMNS parameters
Parameter	Description
db_name	Database name. If this parameter is not specified, the current database is selected.
table_name	Table name.
col_name	Name of a column in a table. Multiple columns are supported. It consists of letters, digits, and underscores (_).

Precautions

After a column is deleted, at least one key column must exist in the schema. Otherwise, an error message is displayed, and the column fails to be deleted.

Examples

Assume that the table contains four columns named a1, b1, c1, and d1.

Delete a column:
ALTER TABLE carbon DROP COLUMNS (b1);

ALTER TABLE test_db.carbon DROP COLUMNS (b1);
Delete multiple columns:
ALTER TABLE carbon DROP COLUMNS (b1,c1);

ALTER TABLE test_db.carbon DROP COLUMNS (b1,c1);