Node.js 中的 PostgreSQL 多行更新 [英] PostgreSQL multi-row updates in Node.js

问题描述

正如我在这里发现的 在 Stackoverflow 上可以通过执行这样的操作来更新一个查询中的多行

As i already found here On Stackoverflow it is possible to update multiple rows in one query by doing something like this

update test as t set
    column_a = c.column_a,
    column_c = c.column_c
from (values
    ('123', 1, '---'),
    ('345', 2, '+++')  
) as c(column_b, column_a, column_c) 
where c.column_b = t.column_b;

特别感谢@Roman Pekar 的明确答复.

special thanks to @Roman Pekar for the clear answer.

现在我正在尝试将这种更新方式与在 NodeJS 中查询 postgreSQL 数据库结合起来.

Now i'm trying to merge this way of updating with querying to a postgreSQL database in NodeJS.

这是我的代码片段:

var requestData = [
    {id: 1, value: 1234}
    {id: 2, value: 5678}
    {id: 3, value: 91011}
]


client.connect(function (err) {
    if (err) throw err;

client.query(buildStatement(requestData), function (err, result) {
    if (err) throw err;

    res.json(result.rows);

    client.end(function (err) {
        if (err) throw err;
    });
});
});


var buildStatement = function(requestData) {
var params = [];
var chunks = [];

for(var i = 0; i < requestData.length; i++) {

    var row = requestData[i];
    var valuesClause = [];

    params.push(row.id);
    valuesClause.push('$' + params.length);
    params.push(row.value);
    valuesClause.push('$' + params.length);

    chunks.push('(' + valuesClause.join(', ') + ')');

}

return {
    text: 'UPDATE fit_ratios as f set ratio_budget = c.ratio_budget from (VALUES ' +  chunks.join(', ') + ') as c(ratio_label, ratio_budget) WHERE c.ratio_label = f.ratio_label', values: params
        }
}

我没有收到错误，但它没有更新我的表，我真的不知道这里出了什么问题.也许我的查询代码中有语法错误?我只是在 NodeJS pg 包中更新时没有找到多行查询的任何具体示例

i don't get an error but it doesn't update my table, i don't really know what goes wrong here. Perhaps a syntax error in my query code? I just don't find any specific examples of multiple row querying when updating in NodeJS pg package

推荐答案

以下示例基于库 pg-promise 及其方法 helpers.更新:

The example below is based on library pg-promise, and its method helpers.update:

// library initialization, usually placed in its own module:
const pgp = require('pg-promise')({
    capSQL: true // capitalize all generated SQL
});

const db = pgp(/*your connection details*/);

// records to be updated:
const updateData = [
    {id: 1, value: 1234},
    {id: 2, value: 5678},
    {id: 3, value: 91011}
];

// declare your ColumnSet once, and then reuse it:
const cs = new pgp.helpers.ColumnSet(['?id', 'value'], {table: 'fit_ratios'});

// generating the update query where it is needed:
const update = pgp.helpers.update(updateData, cs) + ' WHERE v.id = t.id';
//=> UPDATE "fit_ratios" AS t SET "value"=v."value"
//   FROM (VALUES(1,1234),(2,5678),(3,91011))
//   AS v("id","value") WHERE v.id = t.id

// executing the query:
await db.none(update);

这种生成多行更新的方法可以表征为:

This method of generating multi-row updates can be characterized as:

• 非常快，因为它依赖于 ColumnSet为查询生成实现智能缓存
• 完全安全，因为所有数据类型都经过库的查询格式化引擎，以确保所有内容都正确格式化和转义.
• 非常灵活，得益于先进的ColumnConfig 语法支持列定义.
• 非常易于使用，因为 pg-promise 实现了简化的界面.

• very fast, as it relies on type ColumnSet that implements smart caching for query generation
• completely safe, as all data types are going through the library's query formatting engine to make sure everything is formatted and escaped correctly.
• very flexible, due to advanced ColumnConfig syntax supported for the columns definition.
• very easy to use, due to the simplified interface implemented by pg-promise.

请注意，我们在 id 列前面使用了 ? 表示该列是条件的一部分，但不会被更新.有关完整的列语法，请参阅 class Column 和 ColumnConfig 结构.

Note that we use ? in front of column id to indicate that the column is part of the condition, but not to be updated. For complete column syntax see class Column and ColumnConfig structure.

相关问题:多行插入与 pg-promise.

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