db-sql-toolkit

Helps with SQL statements, database migration, and bulk execution.

Installation

npm install db-sql-toolkit

Usage

sql

The sql function is a tagged template function to write SQL statements and include parameters in the correct places.

const id = "1234";
const statement = sql`
    SELECT
        name
        , version
        , author
    FROM package
    WHERE
        id = ${id}
`;

The sql function returns a tuple consisting of the statement and an array of passed parameters. In the returned statement all parameters are replaced by question marks (?).

Hint: You can get syntax highlighting in VS Code by installing an extension: es6-string-html

Nesting

You can nest sql statements:

const where = sql`
    id = ${1234}
`;
const statement = sql`
    SELECT
        name
        , version
        , author
    FROM package
    WHERE
        ${where}
`;

SQL literals

If you want to use variables as SQL literals (where no variables are supported), you can use the sqlLiteral function:

const concatCharacter = "|";
const statement = sql`
    SELECT
        GROUP_CONCAT(name, '${sqlLiteral(concatCharacter)}') AS package_names
    FROM package
    GROUP BY author
`;

This inserts the variable concatCharacter as a literal into the SQL statement.

bulkInsertEntities

Insert many entities in as few operations as possible.

const packages: Package[] = [
    // a lot of packages
]

const getParameters = (package: Package): unknown[] => [
    package.id,
    package.name,
    package.version,
    package.author,
];
const statement = sql`
    INSERT INTO package (
        id
        , name
        , version
        , author
    )
    VALUES (${getParameters})
`;

await bulkInsertEntities(database, packages, statement);

This function (and all bulk* functions) uses the MaxVariableNumber property of the Database and splits the operation into multiple operations, if required.

Important: To use this function you have to pass the function to get the parameters for one entity as the only parameter into the sql function.

bulkExecuteCommand

Executes a SQL statement in as few operations as possible.

Important: To use this function one parameter of the sql function has to be an array.

Warning: Do not use the NOT IN operator. If you do so and the operation cannot be executed in one run, you get wrong results.

bulkGetRows

Selects entities in as few operations as possible.

bulkGetCount

Gets the total number of entities in as few operations as possible. You have to select COUNT(*) in the SQL statement.

migrate

With the help of the migrate function you can execute database upgrades.

import { migrate, Database } from "db-sql-toolkit";

async function upgradeDatabase(database: Database): Promise<void> {
    await migrate({
        database,
        // The targetVersion parameter is optional. If you omit it, the migrationMap will be executed until the last version.
        targetVersion: 3,
        migrationMap: [
            [1, createDatabase],
            [2, updateToVersion2],
            [3, updateToVersion3],
        ]
    });
}



async function createDatabase(database: Database): Promise<void> {
    // Create the initial database.
}

// updateToVersion2 and updateToVersion3 are omitted.

See Database for type information.

It calls all required upgrade functions in the correct order. In the example above, to upgrade the database from version 2 to 3, the function updateToVersion3 will be called.

By default it uses the db_version table (and creates it if needed) to store and update the current version of the database. You can change this by passing your own getCurrentVersion and updateVersion functions to the migrate function:

async function getCurrentVersion(database: Database): Promise<number> {
    // Get the current version of the database.

    return 2;
}

async function updateVersion(database: Database, version: number): Promise<void> {
    // Write the new version into the database.
}

Optionally you can pass a writeLog function to the migrate function, e.g. to print the current and updated version of the database:

function writeLog(message: string): void {
    // Log the message.
}

Types

Database

The Database type is defined as an interface:

interface Database {
    MaxVariableNumber: number;
    executeSqlCommand: (statement: string, parameters: unknown[]) => Promise<void>;
    getRows: <T>(statement: string, parameters: unknown[]) => Promise<T[]>;
}

MaxVariableNumber is the maximum number of parameters per SQL statement.