如何用“ like”查询MongoDB？

您可以使用“ like”轻松查询MongoDB：

db.yourCollectionName.find({"yourFieldName" : /.*yourMatchingValue.*/}).pretty();

为了理解上述语法，让我们创建包含一些文档的集合。在这里，我们有一个名为“ employee”的集合。查询如下：

> db.employee.insert({"EmployeeName":"John","EmployeeSalary":450000});
WriteResult({ "nInserted" : 1 })
> db.employee.insert({"EmployeeName":"Carol","EmployeeSalary":150000});
WriteResult({ "nInserted" : 1 })
> db.employee.insert({"EmployeeName":"James","EmployeeSalary":550000});
WriteResult({ "nInserted" : 1 })
> db.employee.insert({"EmployeeName":"Jace","EmployeeSalary":670000});
WriteResult({ "nInserted" : 1 })
> db.employee.insert({"EmployeeName":"Larry","EmployeeSalary":1000000});
WriteResult({ "nInserted" : 1 })

现在，您可以使用find()方法显示集合中的所有文档。查询如下：

> db.employee.find().pretty();

以下是输出：

{
   "_id" : ObjectId("5c6c0b2e68174aae23f5ef59"),
   "EmployeeName" : "John",
   "EmployeeSalary" : 450000
}
{
   "_id" : ObjectId("5c6c0b3b68174aae23f5ef5a"),
   "EmployeeName" : "Carol",
   "EmployeeSalary" : 150000
}
{
   "_id" : ObjectId("5c6c0b4768174aae23f5ef5b"),
   "EmployeeName" : "James",
   "EmployeeSalary" : 550000
}
{
   "_id" : ObjectId("5c6c0b8f68174aae23f5ef5c"),
   "EmployeeName" : "Jace",
   "EmployeeSalary" : 670000
}
{
   "_id" : ObjectId("5c6c0b9e68174aae23f5ef5d"),
   "EmployeeName" : "Larry",
   "EmployeeSalary" : 1000000
}

这是MongoDB中带有“ like”运算符的查询：

> db.employee.find({"EmployeeName":/.*J.*/}).pretty();

以下是输出：

{
   "_id" : ObjectId("5c6c0b2e68174aae23f5ef59"),
   "EmployeeName" : "John",
   "EmployeeSalary" : 450000
}
{
   "_id" : ObjectId("5c6c0b4768174aae23f5ef5b"),
   "EmployeeName" : "James",
   "EmployeeSalary" : 550000
}
{
   "_id" : ObjectId("5c6c0b8f68174aae23f5ef5c"),
   "EmployeeName" : "Jace",
   "EmployeeSalary" : 670000
}