:
(冒号)运算符
适用于: Databricks SQL Databricks Runtime
使用 JSON 路径表达式从 JSON 字符串中提取内容。
语法
jsonExpr : jsonPath
参数
jsonExpr
:使用有效 JSON 的VARIANT
表达式或STRING
表达式。jsonPath
:JSON 路径表达式。
返回
结果与类型 jsonExpr
匹配。 如果输入不是有效的 JSON 或路径表达式对于 JSON 值无效,则结果为 NULL
。
如果提取的值是未分隔的 null
,则结果是 NULL
值。
有关有效 JSON 路径的详细说明,请参阅 JSON 路径表达式。
示例
> SELECT c1:price
FROM VALUES('{ "price": 5 }') AS T(c1);
5
> SELECT c1:['price']::decimal(5,2)
FROM VALUES('{ "price": 5 }') AS T(c1);
5.00
> SELECT c1:item[1].price::double
FROM VALUES('{ "item": [ { "model" : "basic", "price" : 6.12 },
{ "model" : "medium", "price" : 9.24 } ] }') AS T(c1);
9.24
> SELECT c1:item[*].price
FROM VALUES('{ "item": [ { "model" : "basic", "price" : 6.12 },
{ "model" : "medium", "price" : 9.24 } ] }') AS T(c1);
[6.12,9.24]
> SELECT from_json(c1:item[*].price, 'ARRAY<DOUBLE>')[0]
FROM VALUES('{ "item": [ { "model" : "basic", "price" : 6.12 },
{ "model" : "medium", "price" : 9.24 } ] }') AS T(c1);
6.12
> SELECT from_json(c1:item[*], 'ARRAY<STRUCT<model STRING, price DOUBLE>>')
FROM VALUES('{ "item": [ { "model" : "basic", "price" : 6.12 },
{ "model" : "medium", "price" : 9.24 } ] }') AS T(c1);
[{"model":"basic","price":6.12},{"model":"medium","price":9.24}]
> SELECT inline(from_json(c1:item[*], 'ARRAY<STRUCT<model STRING, price DOUBLE>>'))
FROM VALUES('{ "item": [ { "model" : "basic", "price" : 6.12 },
{ "model" : "medium", "price" : 9.24 } ] }') AS T(c1);
basic 6.12
medium 9.24
-- Examples with VARIANT expressions.
> SELECT PARSE_JSON('{ "price": 5 }'):price
5
> SELECT PARSE_JSON('{ "price": 5 }'):price::decimal(5,2)
5.00
> SELECT PARSE_JSON('{ "item": [ { "model" : "basic", "price" : 6.12 },
{ "model" : "medium", "price" : 9.24 } ] }'):item[1].price::double
9.24