我需要一个查询来在 Bigquery 中查找表的列名（表元数据），例如 SQL 中的以下查询：
SELECT column_name,data_type,data_length,data_precision,nullable FROM all_tab_cols where table_name ='EMP';
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6 回答
35
BigQuery 现在支持信息架构。
假设您有一个名为 MY_PROJECT.MY_DATASET 的数据集和一个名为 MY_TABLE 的表，那么您可以运行以下查询：
SELECT column_name
FROM MY_PROJECT.MY_DATASET.INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'MY_TABLE'
于 2019-05-07T16:28:22.430 回答
9
是的，您可以使用INFORMATION_SCHEMA获取表元数据。
过去链接中提到的示例之一从INFORMATION_SCHEMA.COLUMN_FIELD_PATHSgithub_repos 数据集中的提交表的视图中检索元数据，您只需要
在 GCP Console 中打开 BigQuery 网页界面。
在查询编辑器框中输入以下标准 SQL 查询。INFORMATION_SCHEMA 需要标准的 SQL 语法。标准 SQL 是 GCP Console 中的默认语法。
SELECT * FROM `bigquery-public-data`.github_repos.INFORMATION_SCHEMA.COLUMN_FIELD_PATHS WHERE table_name="commits" AND column_name="author" OR column_name="difference"
注意：INFORMATION_SCHEMA 视图名称区分大小写。
- 单击运行。
结果应如下所示
+------------+-------------+---------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| table_name | column_name | field_path | data_type | description |
+------------+-------------+---------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| commits | author | author | STRUCT<name STRING, email STRING, time_sec INT64, tz_offset INT64, date TIMESTAMP> | NULL |
| commits | author | author.name | STRING | NULL |
| commits | author | author.email | STRING | NULL |
| commits | author | author.time_sec | INT64 | NULL |
| commits | author | author.tz_offset | INT64 | NULL |
| commits | author | author.date | TIMESTAMP | NULL |
| commits | difference | difference | ARRAY<STRUCT<old_mode INT64, new_mode INT64, old_path STRING, new_path STRING, old_sha1 STRING, new_sha1 STRING, old_repo STRING, new_repo STRING>> | NULL |
| commits | difference | difference.old_mode | INT64 | NULL |
| commits | difference | difference.new_mode | INT64 | NULL |
| commits | difference | difference.old_path | STRING | NULL |
| commits | difference | difference.new_path | STRING | NULL |
| commits | difference | difference.old_sha1 | STRING | NULL |
| commits | difference | difference.new_sha1 | STRING | NULL |
| commits | difference | difference.old_repo | STRING | NULL |
| commits | difference | difference.new_repo | STRING | NULL |
+------------+-------------+---------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
于 2019-09-25T10:13:10.073 回答
4
对于像我这样的新手，上面的语法如下：
select * from project_name.dataset_name.INFORMATION_SCHEMA.COLUMNS where table_catalog=project_name and table_schema=dataset_name and table_name=table_name
于 2019-05-22T01:56:32.763 回答
3
更新：这现在是可能的！请参阅下面的INFORMATION SCHEMA文档和答案。
答案，大约在 2012 年：
目前无法通过查询检索表元数据（即列名和类型），尽管这不是第一次被请求。
您是否有理由需要将此作为查询？表元数据可通过表 API获得。
于 2012-07-05T07:11:27.087 回答
2
实际上，使用 SQL 可以做到这一点。为此，您需要查询正在创建的此特定表的最后一个日志的日志记录表。
例如，假设表每天加载/创建：
CREATE TEMP FUNCTION jsonSchemaStringToArray(jsonSchema String)
RETURNS ARRAY<STRING> AS ((
SELECT
SPLIT(
REGEXP_REPLACE(REPLACE(LTRIM(jsonSchema,'{ '),'"fields": [',''), r'{[^{]+"name": "([^\"]+)"[^}]+}[, ]*', '\\1,')
,',')
));
WITH valid_schema_columns AS (
WITH array_output aS (SELECT
jsonSchemaStringToArray(jsonSchema) AS column_names
FROM (
SELECT
protoPayload.serviceData.jobInsertRequest.resource.jobConfiguration.load.schemaJson AS jsonSchema
, ROW_NUMBER() OVER (ORDER BY metadata.timestamp DESC) AS record_count
FROM `realself-main.bigquery_logging.cloudaudit_googleapis_com_data_access_20170101`
WHERE
protoPayload.serviceData.jobInsertRequest.resource.jobConfiguration.load.destinationTable.tableId = '<table_name>'
AND
protoPayload.serviceData.jobInsertRequest.resource.jobConfiguration.load.destinationTable.datasetId = '<schema_name>'
AND
protoPayload.serviceData.jobInsertRequest.resource.jobConfiguration.load.createDisposition = 'CREATE_IF_NEEDED'
) AS t
WHERE
t.record_count = 1 -- grab the latest entry
)
-- this is actually what UNNESTS the array into standard rows
SELECT
valid_column_name
FROM array_output
LEFT JOIN UNNEST(column_names) AS valid_column_name
)
于 2017-04-22T19:55:45.770 回答
0
要检查列，您可以通过 CLI 访问您的表 轻松简单地查找
bq query --use_legacy_sql=false 'select Hour, sum(column 1) as column from `project_id.dataset.table_name` where Date(Hour) = '2020-06-10';'
于 2020-06-13T20:09:12.687 回答