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92 lines
2.5 KiB
TypeScript
92 lines
2.5 KiB
TypeScript
import fs = require("fs");
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import * as SQL from "sql.js";
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var DB_PATH = "data.db";
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function createFile(path: string): void {
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var fd = fs.openSync(path, "a");
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fs.closeSync(fd);
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}
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// Open the database file. If it does not exist, create a blank database in memory.
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var databaseData: Buffer;
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databaseData = fs.existsSync(DB_PATH) ? fs.readFileSync(DB_PATH) : null;
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var db = new SQL.Database(databaseData);
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// Create a new table 'test_table' in the database in memory.
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var createTableStatement =
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"DROP TABLE IF EXISTS test_table;" +
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"CREATE TABLE test_table (id INTEGER PRIMARY KEY, content TEXT);";
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db.run(createTableStatement);
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// Insert 2 records for testing.
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var insertRecordStatement =
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"INSERT INTO test_table (id, content) VALUES (@id, @content);";
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db.run(insertRecordStatement, {
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"@id": 1,
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"@content": "Content 1"
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});
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db.run(insertRecordStatement, {
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"@id": 2,
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"@content": "Content 2"
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});
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var n = db.getRowsModified();
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try {
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// This query will throw exception: primary key constraint failed.
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db.run(insertRecordStatement, {
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"@id": 1,
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"@content": "Content 3"
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});
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} catch (ex) {
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console.warn(ex);
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}
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// A simple SELECT query.
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var selectRecordStatement =
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"SELECT * FROM test_table WHERE id = @id;"
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var selectStatementObject = db.prepare(selectRecordStatement);
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var results = selectStatementObject.get({
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"@id": 1
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});
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console.log(results);
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selectStatementObject.free();
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// Access the results one by one, asynchronously.
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var selectRecordsStatement =
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"SELECT * FROM test_table;";
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db.each(
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selectRecordsStatement,
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(obj: { [columnName: string]: number | string | Uint8Array }): void => {
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console.log(obj);
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},
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(): void => {
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console.info("Iteration done.");
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dbAccessDone();
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});
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function dbAccessDone(): void {
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// Save the database into SQLite version 3 format.
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if (!fs.existsSync(DB_PATH)) {
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createFile(DB_PATH);
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}
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var exportedData = db.export();
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fs.writeFileSync(DB_PATH, exportedData);
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// Finally, close the database connection and release the resources in memory.
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db.close();
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}
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// Create a database
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var db2 = new SQL.Database();
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// You can also use javascript functions inside your SQL code
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// Create the js function you need
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function add(a: number, b: number): number {return a+b;}
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// Specifies the SQL function's name, the number of it's arguments, and the js function to use
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db2.create_function("add_js", add);
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// Run a query in which the function is used
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db2.run("INSERT INTO hello VALUES (add_js(7, 3), add_js('Hello ', 'world'));"); // Inserts 10 and 'Hello world'
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