问题描述
这是我的 sql:
SELECT
JSON_OBJECTAGG(table_name,columns)
FROM (
SELECT
table_name,JSON_OBJECTAGG(column_name,data_type) as columns
FROM `COLUMNS`
WHERE
`TABLE_SCHEMA` = 'my_db'
GROUP BY table_name
) table_columns
问题出在JSON_OBJECTAGG(table_name,columns)
,列变成了字符串。如何将其转换为 JSON?
解决方法
使用JSON_EXTRACT(column_value_in_json,'$')
SELECT
JSON_OBJECTAGG(table_name,JSON_EXTRACT(
columns,'$'
)
)
FROM (
SELECT
table_name,JSON_OBJECTAGG(column_name,data_type) as columns
FROM `COLUMNS`
WHERE
`TABLE_SCHEMA` = 'my_db'
GROUP BY table_name
) table_columns