var documents = new BsonDocument[]
{
    new BsonDocument
    {
        { "item", "journal" },
        { "qty", 25 },
        { "size", new BsonDocument { { "h", 14 }, { "w", 21 }, {  "uom", "cm"} } },
        { "status", "A" }
    },
    new BsonDocument
    {
        { "item", "notebook" },
        { "qty", 50 },
        { "size", new BsonDocument { { "h",  8.5 }, { "w", 11 }, {  "uom", "in"} } },
        { "status", "A" }
    },
    new BsonDocument
    {
        { "item", "paper" },
        { "qty", 100 },
        { "size", new BsonDocument { { "h",  8.5 }, { "w", 11 }, {  "uom", "in"} } },
        { "status", "D" }
    },
    new BsonDocument
    {
        { "item", "planner" },
        { "qty", 75 },
        { "size", new BsonDocument { { "h", 22.85 }, { "w", 30  }, {  "uom", "cm"} } },
        { "status", "D" }
    },
    new BsonDocument
    {
        { "item", "postcard" },
        { "qty", 45 },
        { "size", new BsonDocument { { "h", 10 }, { "w", 15.25 }, {  "uom", "cm"} } },
        { "status", "A" }
    },
};
collection.InsertMany(documents);
 

查詢集合中的全部文件

若要選擇集合中的所有文件，請將空文件作為查詢篩選器引數傳遞給find方法。查詢篩選器引數確定選擇標準：

var filter = Builders<BsonDocument>.Filter.Empty;
var result = collection.Find(filter).ToList();

此操作對應於以下SQL語句：

SELECT * FROM inventory

指定相等條件

指定相等條件，使用Eq方法構建一個過濾器

Builders<BsonDocument>.Filter.Eq(<field>, <value>);
 

以下示例查詢 inventory集合的全部文件，條件是 status="D":

var filter = Builders<BsonDocument>.Filter.Eq("status", "D");
var result = collection.Find(filter).ToList();

此操作對應於以下SQL語句：

SELECT * FROM inventory WHERE status = "D"

使用查詢操作符指定條件

除了相等過濾器，MongoDB還提供了多種查詢操作符來生成過濾器，以下示例使用 FilterDefinitionBuilder 方法建立文件的過濾器:

var builder = Builders<BsonDocument>.Filter;
builder.And(builder.Eq(<field1>, <value1>), builder.Lt(<field2>, <value2>));

The following example retrieves all documents from the inventory collection where status equals either "A" or "D":

var filter = Builders<BsonDocument>.Filter.In("status", new[] { "A", "D" });
var result = collection.Find(filter).ToList();

NOTE

Although you can express this query using the $or operator, use the $in operator rather than the $oroperator when performing equality checks on the same field.

The operation corresponds to the following SQL statement:

SELECT * FROM inventory WHERE status in ("A", "D")

Refer to the Query and Projection Operators document for the complete list of MongoDB query operators.

Specify AND Conditions

A compound query can specify conditions for more than one field in the collection’s documents. Implicitly, a logical AND conjunction connects the clauses of a compound query so that the query selects the documents in the collection that match all the conditions.

The following example retrieves all documents in the inventory collection where the status equals "A" andqty is less than ($lt) 30:

var builder = Builders<BsonDocument>.Filter;
var filter = builder.And(builder.Eq("status", "A"), builder.Lt("qty", 30));
var result = collection.Find(filter).ToList();

The operation corresponds to the following SQL statement:

SELECT * FROM inventory WHERE status = "A" AND qty < 30

See comparison operators for other MongoDB comparison operators.

Specify OR Conditions

Using the $or operator, you can specify a compound query that joins each clause with a logical OR conjunction so that the query selects the documents in the collection that match at least one condition.

The following example retrieves all documents in the collection where the status equals "A" or qty is less than ($lt) 30:

var builder = Builders<BsonDocument>.Filter;
var filter = builder.Or(builder.Eq("status", "A"), builder.Lt("qty", 30));
var result = collection.Find(filter).ToList();

The operation corresponds to the following SQL statement:

SELECT * FROM inventory WHERE status = "A" OR qty < 30

NOTE

Specify AND as well as OR Conditions

In the following example, the compound query document selects all documents in the collection where the status equals "A" and either qty is less than ($lt) 30 or item starts with the character p:

var builder = Builders<BsonDocument>.Filter;
var filter = builder.And(
    builder.Eq("status", "A"),
    builder.Or(builder.Lt("qty", 30), builder.Regex("item", new BsonRegularExpression("^p"))));
var result = collection.Find(filter).ToList();

The operation corresponds to the following SQL statement:

SELECT * FROM inventory WHERE status = "A" AND ( qty < 30 OR item LIKE "p%")

NOTE

MongoDB supports regular expressions $regex queries to perform string pattern matches.