用SQL查詢JSON數據：Charlatan

Charlatan是一個各種格式列表或流記錄的查詢引擎。它默認支持CSV或JSON格式，但可以輕松擴展支付其它格式。它提供了一種類似SQL的語言來查詢數據值。

查詢語法

SELECT <fields> FROM <source> [ WHERE <value> ] [ STARTING AT <index> ]

• <fields>is a list of comma-separated field names. Each field name must exist in the source. When reading CSV files, the field names are the column names, while when reading JSON they represent keys.
• <source>is the filename from which the data is read. The API is agnostique on this and one can implement support for any source type.
• <value>is a SQL-like value, which can be either a constant (e.g.WHERE 1), a field (e.g.WHERE archived) or any operation using comparison operators (=,!=,<,<=,>,>=,AND,OR) and optionally parentheses (e.g.WHERE (foo > 2) AND (bar = "yo")). The parser allows to use&&instead ofANDand||instead ofOR.
• <index>can be used to skip the first N records.
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Constant values include strings, integers, floats, booleans and thenullvalue.

示例

SELECT CountryName FROM sample/csv/population.csv WHERE Year = 2010 AND Value > 50000000 AND Value < 70000000
SELECT name, age FROM sample/json/people.jsons WHERE stats.walking > 30 AND stats.biking < 300

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