querying

Query a single document from Firestore in Flutter (cloud_firestore Plugin)

由 那年仲夏 提交于 2019-11-27 15:05:08
问题 I want to retrieve data of only a single document via its ID. My approach with example data of: TESTID1 { 'name': 'example', 'data': 'sample data', } was something like this: Firestore.instance.document('TESTID1').get() => then(function(document) { print(document('name')); } but that does not seem to be correct syntax. I was not able to find any detailed documentation on querying firestore within flutter (dart) since the firebase documentation only addresses Native WEB, iOS, Android etc. but

Nested select statement in SQL Server

由 孤街浪徒 提交于 2019-11-27 02:36:07
Why doesn't the following work? SELECT name FROM (SELECT name FROM agentinformation) I guess my understanding of SQL is wrong, because I would have thought this would return the same thing as SELECT name FROM agentinformation Doesn't the inner select statement create a result set which the outer SELECT statement then queries? You need to alias the subquery. SELECT name FROM (SELECT name FROM agentinformation) a or to be more explicit SELECT a.name FROM (SELECT name FROM agentinformation) a Somnath Muluk Answer provided by Joe Stefanelli is already correct. SELECT name FROM (SELECT name FROM

Nested select statement in SQL Server

由 冷暖自知 提交于 2019-11-26 10:06:53
问题 Why doesn\'t the following work? SELECT name FROM (SELECT name FROM agentinformation) I guess my understanding of SQL is wrong, because I would have thought this would return the same thing as SELECT name FROM agentinformation Doesn\'t the inner select statement create a result set which the outer SELECT statement then queries? 回答1: You need to alias the subquery. SELECT name FROM (SELECT name FROM agentinformation) a or to be more explicit SELECT a.name FROM (SELECT name FROM

Is there a query language for JSON?

由 你。 提交于 2019-11-26 05:41:16
Is there a (roughly) SQL or XQuery-like language for querying JSON? I'm thinking of very small datasets that map nicely to JSON where it would be nice to easily answer queries such as "what are all the values of X where Y > 3" or to do the usual SUM / COUNT type operations. As completely made-up example, something like this: [{"x": 2, "y": 0}}, {"x": 3, "y": 1}, {"x": 4, "y": 1}] SUM(X) WHERE Y > 0 (would equate to 7) LIST(X) WHERE Y > 0 (would equate to [3,4]) I'm thinking this would work both client-side and server-side with results being converted to the appropriate language-specific data

Is there a query language for JSON?

由 浪子不回头ぞ 提交于 2019-11-26 01:55:48
问题 Is there a (roughly) SQL or XQuery-like language for querying JSON? I\'m thinking of very small datasets that map nicely to JSON where it would be nice to easily answer queries such as \"what are all the values of X where Y > 3\" or to do the usual SUM / COUNT type operations. As completely made-up example, something like this: [{\"x\": 2, \"y\": 0}}, {\"x\": 3, \"y\": 1}, {\"x\": 4, \"y\": 1}] SUM(X) WHERE Y > 0 (would equate to 7) LIST(X) WHERE Y > 0 (would equate to [3,4]) I\'m thinking
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