MongoDB Learning Notes (ii)

MongoDB Basic Operation Update

Update method parameters

// query: Conditions for Updates // obj: Updated object // Boolean type, true: No new, false: Update only not new // Multi: Whether to allow bulk updates function (query, obj, Upsert, multi) {    //dosomething}

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Document substitution:

var where={    "age": +}; var p1 = db.user.findOne (where);p 1.age+ +; // age Self-increment 1db.user.update (WHERE,P1); // Replace the first document that matches to a new document

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Common modifiers:

1. $set modifier: The $set modifier is used to modify the value of a field in a document, which is added if the field does not exist.

   var where={    "_id": ObjectId ("5634b21827480baffb199df4")}; var action={    "$set": {"hobby": "Run"}//$set modifier Updates or adds the specified field } Db.user.update (where,action); // Add a hoppy field for Deng Chao

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   Modify the type of a field

   var where={    "_id": ObjectId ("5634b21827480baffb199df4")}; var action={    "$set": {"hoppy": ["Run", "Sing", "Dance"]}// Change the previous hoppy field to an interest array }db.user.update (where,action);

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   Modify fields in an inline document

   varWhere={    "_id": ObjectId ("5634b21827480baffb199df4")};varaction={    "$set":    {        "Family":        {            "Wife": "Sun Li",            "Father": "Unknown",            "Monther": "Unknown",            "Sons": ["Deng Han", "Deng Han One"]}}} ;d b.user.update (where,action);//added Deng's super family relationship dataaction={    "$set": {"Family.father": "Deng"}//Change the Father field in the Deng Hyper Relationship document to Deng}db.user.update (where,action);

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   Delete a field from a document

   var where={    "_id": ObjectId ("5634b21827480baffb199df4")}; var action={    "$unset": {"Family.wife": 1}//$unset operator for removing a field }; Db.user.update (where,action);

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3. $inc modifier: self-increment or decrement modifier, atomic operation.

    var  where={ "_id": ObjectId (" 5634b21827480baffb199df4 ")};  var  action={ "$inc": {"Age": 1}//  Age auto-increment 1,-1 is self-decrement, the operator can only be used for numeric types, otherwise it will be abnormal   

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5. $push Operator: Adds an element to the end of an array, and if the specified array does not exist, the array is created

    var  Where={ "_id": ObjectId ("5634b21827480baffb199df4"  var  action={ "$push": {"family.sons": " Deng Zi "}//  add an element to the end of the sons array, and if the sons array does not exist, it will be created   

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7. $each Operator: The $push operator with the $each operator enables you to add multiple elements to an array at once

    var  Where={ "_id": ObjectId ("5634b21827480baffb199df4"  var  action={ "$push": {"family.sons": {" $each ": [" Deng Zi qi "," Dengxiao "," Deng Jiu Mei "]}}//   

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9. $slice operator: Used to set the length of the array, when the value is positive, only the first n elements in the array are preserved, negative, the last n elements in the array are preserved

    var  Where={ "_id": ObjectId ("5634b21827480baffb199df4"  var  action={ "$push": {"family.sons": {" $each ": [" Deng Zi qi "," Deng Han One "," Deng Han "]," $slice ": -2}}//   

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11. $sort Operator: Sort elements in an array

     { "_id": ObjectId ("5634b21827480baffb199df4"  var  action={ "$push": {"family.sons": {" $each ": [" Deng Zi qi "," Deng Han One "," Deng Han "]," $sort ": -1}}//   ";d b.user.update (where,action);  

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13. $addToSet Operator: Adds a new element to the array and only adds

     var  where={ "_id": ObjectId ("5634b21827480baffb199df4"  var  action={ "$addToSet": {"family.sons ": {" $each ": [" Deng Zi qi "," Deng Han XI "]," $sort ": -1}}//   ";d B.user.update (where,action) only if the element is not in the array;  

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15. $pop Operator: Removes an element from the top or tail of an array, which can be used to simulate a queue or stack

     var  where= { "_id": ObjectId ("5634b21827480baffb199df4" ) }; var  action={ "$pop": {"family.sons":-1} //   

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17. $pull operator: Deletes all matching elements in the array

    var where={    "_id": ObjectId ("5634b21827480baffb199df4")}; var action={    "$pull": {"family.sons": "Deng Han One"}// Delete all specified elements in the specified array }; Db.user.update (where,action);d B.runcommand ("GetLastError");

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19. To modify an element by the position of an array element:

20. var where={    "_id": ObjectId ("5634b21827480baffb199df4")}; var action={    "$inc": {"Age": -5},// 5    "$set": {"family.sons.0": "Deng Zi qi" "},// Modify the value of the first element in the sons array directly by subscript: Deng Zi ;d b.user.update (where,action);

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    Use the locator:

    var where={    "family.sons.name": "Deng Zi qi"}; The var action={    //$ symbol is automatically positioned to match the array elements, such as the first match to the array element subscript 3, then $ can actually be considered to be 3    "$ Set ": {" Family.sons.$.name ":" Dengxiao "},};d b.user.update (where,action);

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22. findandmodify function: Update and return a document

    db.user.findAndModify ({    // query condition    // Sort method    update: {$set: { Name: ' Zhang Jie '}, $inc: {age:2}},// Update, or use Remove:true to execute delete    new:true//  Returns the updated document });

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MongoDB Learning Notes (ii)