--- machine_translated: true machine_translated_rev: 5decc73b5dc60054f19087d3690c4eb99446a6c3 --- # 系统。列 {#system-columns} 包含有关所有表中列的信息。 您可以使用此表获取类似于以下内容的信息 [DESCRIBE TABLE](../../sql-reference/statements/misc.md#misc-describe-table) 查询,但对于多个表一次。 该 `system.columns` 表包含以下列(列类型显示在括号中): - `database` (String) — Database name. - `table` (String) — Table name. - `name` (String) — Column name. - `type` (String) — Column type. - `default_kind` (String) — Expression type (`DEFAULT`, `MATERIALIZED`, `ALIAS`)为默认值,如果没有定义,则为空字符串。 - `default_expression` (String) — Expression for the default value, or an empty string if it is not defined. - `data_compressed_bytes` (UInt64) — The size of compressed data, in bytes. - `data_uncompressed_bytes` (UInt64) — The size of decompressed data, in bytes. - `marks_bytes` (UInt64) — The size of marks, in bytes. - `comment` (String) — Comment on the column, or an empty string if it is not defined. - `is_in_partition_key` (UInt8) — Flag that indicates whether the column is in the partition expression. - `is_in_sorting_key` (UInt8) — Flag that indicates whether the column is in the sorting key expression. - `is_in_primary_key` (UInt8) — Flag that indicates whether the column is in the primary key expression. - `is_in_sampling_key` (UInt8) — Flag that indicates whether the column is in the sampling key expression. [原文](https://clickhouse.tech/docs/zh/operations/system-tables/columns)