Su, Xiaomeng 76a5b1ee83 dli_sqlreference_20240227

Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Su, Xiaomeng <suxiaomeng1@huawei.com>
Co-committed-by: Su, Xiaomeng <suxiaomeng1@huawei.com>

2024-03-27 22:02:33 +00:00

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Modifying Column Comments

Function

You can modify the column comments of non-partitioned or partitioned tables.

Syntax

ALTER TABLE [db_name.]table_name CHANGE COLUMN col_name col_name col_type COMMENT 'col_comment';

Keywords

CHANGE COLUMN: Modify a column.
COMMENT: column description

Parameters

**Table 1** Parameters
Parameter	Mandatory	Description
db_name	No	Database name. Only letters, digits, and underscores (_) are allowed. The name cannot contain only digits or start with an underscore (_).
table_name	Yes	Table name
col_name	Yes	Column name. The value must be the name of an existing column.
col_type	Yes	Column data type specified when the table is created, which cannot be modified.
col_comment	Yes	Column comment after modification. The comment can contain a maximum of 1024 bytes.

Example

Change the comment of the c1 column in the t1 table to the new comment.

1
ALTER TABLE t1 CHANGE COLUMN c1 c1 STRING COMMENT 'the new comment';

Parent topic: Modifying a Table

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