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DocumentDB SQL - Where子句

DocumentDB SQL Where子句 - 从Overview,Select Clause,From Clause,Where子句,Operators,Keyword,In Keyword,Value Keyword,Order By Clause,Iteration,Joins,Aliasing,Array Creation,简单而简单的步骤学习DocumentDB SQL标量表达式,参数化SQL,内置函数,Linq到SQL转换,JavaScript集成,用户定义函数,复合SQL查询。

在本章中,我们将介绍WHERE子句,它也是可选的FROM子句.它用于在以源提供的JSON文档的形式提取数据时指定条件.任何JSON文档都必须将指定条件评估为"true"才能考虑结果.如果满足给定条件,则只返回JSON文档形式的特定数据.我们可以使用WHERE子句来过滤记录并仅获取必要的记录.

我们将在本例中考虑相同的三个文档.以下是 AndersenFamily 文件.

{    "id": "AndersenFamily",    "lastName": "Andersen",    "parents": [       { "firstName": "Thomas", "relationship":  "father" },       { "firstName": "Mary Kay", "relationship":  "mother" }    ],    "children": [       {          "firstName": "Henriette Thaulow",          "gender": "female",          "grade": 5,          "pets": [ { "givenName": "Fluffy", "type":  "Rabbit" } ]       }    ],   "location": { "state": "WA", "county": "King", "city": "Seattle" },    "isRegistered": true }

以下是 SmithFamily 文件.

{    "id": "SmithFamily",    "parents": [       { "familyName": "Smith", "givenName": "James" },       { "familyName": "Curtis", "givenName": "Helen" }    ],   "children": [        {          "givenName": "Michelle",          "gender": "female",          "grade": 1       },      {          "givenName": "John",          "gender": "male",          "grade": 7,         "pets": [             { "givenName": "Tweetie", "type": "Bird" }          ]       }    ],   "location": {       "state": "NY",       "county": "Queens",       "city": "Forest Hills"    },   "isRegistered": true }

以下是 WakefieldFamily 文件.

{    "id": "WakefieldFamily",    "parents": [       { "familyName": "Wakefield", "givenName": "Robin" },       { "familyName": "Miller", "givenName": "Ben" }    ],    "children": [       {          "familyName": "Merriam",          "givenName": "Jesse",          "gender": "female",          "grade": 6,          "pets": [            { "givenName": "Charlie Brown", "type": "Dog" },             { "givenName": "Tiger", "type": "Cat" },             { "givenName": "Princess", "type": "Cat" }          ]       },      {          "familyName": "Miller",          "givenName": "Lisa",          "gender": "female",          "grade": 3,          "pets": [             { "givenName": "Jake", "type": "Snake" }          ]       }    ],   "location": { "state": "NY", "county": "Manhattan", "city": "NY" },    "isRegistered": false }

让我们看一个使用WHERE子句的简单示例.

WHERE条款

在此查询中,在WHE中指定了RE子句,(WHERE f.id ="WakefieldFamily")条件.

SELECT * FROM f  WHERE f.id = "WakefieldFamily"

执行上述查询时,它将返回WakefieldFamily的完整JSON文档,如以下输出所示.

[    {       "id": "WakefieldFamily",       "parents": [          {             "familyName": "Wakefield",             "givenName": "Robin"          },         {             "familyName": "Miller",             "givenName": "Ben"          }       ],      "children": [          {             "familyName": "Merriam",             "givenName": "Jesse",             "gender": "female",             "grade": 6,            "pets": [                {                   "givenName": "Charlie Brown",                   "type": "Dog"                },                {                   "givenName": "Tiger",                   "type": "Cat"                },                {                   "givenName": "Princess",                   "type": "Cat"                }             ]          },          {             "familyName": "Miller",             "givenName": "Lisa",             "gender": "female",             "grade": 3,             "pets": [                {                   "givenName": "Jake",                   "type": "Snake"                }            ]         }       ],      "location": {          "state": "NY",          "county": "Manhattan",          "city": "NY"       },      "isRegistered": false,       "_rid": "Ic8LAJFujgECAAAAAAAAAA==",       "_ts": 1450541623,       "_self": "dbs/Ic8LAA==/colls/Ic8LAJFujgE=/docs/Ic8LAJFujgECAAAAAAAAAA==/",       "_etag": "00000500-0000-0000-0000-567582370000",       "_attachments": "attachments/"    } ]