Node. jssequencee implements single-instance fields or batch auto-increment and auto-Subtraction

Sequencee can perform auto-increment and auto-increment operations on one or more fields of a single instance, or perform batch auto-increment and auto-increment operations on data that meet the conditions. The auto-increment and auto-increment of a single Instance field can be implemented using the corresponding method of Instance, while the batch auto-increment and auto-increment must be implemented using the literal method provided by sequencee. Let's take a look at the detailed introduction. I. Auto-increment and auto-increment for a single instance

In sequencee, an Instance indicates a row of records in the database. There are two types of instances: non-persistent instances created by Model. build () and persistent instances created by Model. create. Whether it is a persistent or non-persistent instance, there will be two methods on the increment () and decrement (), respectively used for the field value auto-increment and auto-increment operations.

Instance. increment (fields, [options])-field value auto-increment

Instance. decrement (fields, [options])-field value auto-Subtraction

For example, find a user whose id is 1 and increase its age by 1:

var User = sequelize.import('../lib/model/user/user');User.findById(1).then(function(user){ user.increment('age').then(function(user){ console.log('success'); })})

The SQL statement generated by the increment () method is as follows:

UPDATE `user` SET `age`=`age` + 1 WHERE `id` = 1

The default auto-increment and auto-impairment values of increment () and decrement () are 1. If you want to use other values, you can use the by parameter in Option [options.

For example, you can reduce the number and age fields by 2 in the following ways:

user.increment(['age', 'number'], {by:2}).then(function(user){ console.log('success');})

The generated SQL statement is as follows:

UPDATE `user` SET `age`=`age` + 2,`number`=`number` + 2 WHERE `id` = 1

Fields parameters can also be passed in through objects, and auto-increment and auto-impairment can be specified. In this case, the options. by parameter is ignored.

For example, increase the number of users by 2 and reduce the age by 1:

user.increment({age:-1, number:2}, {by:5}).then(function(user){ console.log('success');})

The generated SQL statement is as follows:

UPDATE `user` SET `age`=`age` + -1,`number`=`number` + 2 WHERE `id` = 1

Ii. Batch auto-increment and auto-Increment

Both increment () and decrement () perform auto-increment or auto-increment operations on a single instance, that is, the operation data is a row of data in the database. To perform operations similar to batch auto-increment and auto-increment operations, you cannot perform operations through the Instance:

UPDATE `user` SET `age`=`age` + 1 WHERE `number` > 10;

In sequencee, a volume operation is generally implemented through a Model. However, the Model does not have the increment () and decrement () methods, so you cannot perform auto-increment or auto-increment as conveniently as the Instance.

In this case, we can use Model. update () and the top-level method sequencee. literal () in sequencee to implement:

Sequencee. literal (val)-create a literal object

The sequencee. literal () method is used to create a literal object. The object (val) is directly passed into the generated SQL statement without any escape.

For example, increase the age of a user whose number is greater than 10 by 1:

User.update({sex:sequelize.literal('`age` +1')}, {where:{number:{$gt:10}}}).then(function(user){ console.log('success');})

The generated SQL statement is as follows:

UPDATE `user` SET `age`=`age` +1 WHERE `number` > 10

Summary

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