alasql/src/20database.js

AlaSQL.js - JavaScript SQL database library for relational and graph data manipulation with support of localStorage, IndexedDB, and Excel

/*
//
// Database class for Alasql.js
// Date: 03.11.2014
// (c) 2014, Andrey Gershun
//
*/

// Main Database class
/**
    @class Database 
 */

var Database = alasql.Database = function (databaseid) {
	var self = this;
	if(self === alasql) {
		if(databaseid) {
//			if(alasql.databases[databaseid]) {
				self = alasql.databases[databaseid];
//			} else {
				alasql.databases[databaseid] = self;
//			}
			if(!self) {
				throw new Error('Database "'+databaseid+'" not found');
			}
		} else {
			// Create new database (or get alasql?)
			self = alasql.databases.alasql;
			// For SQL Server examples, USE tempdb
			if(alasql.options.tsql) alasql.databases.tempdb = alasql.databases.alasql;
//			self = new Database(databaseid); // to call without new
		}
	}
	if(!databaseid) {
		databaseid = "db"+(alasql.databasenum++); // Random name
	};
	self.databaseid = databaseid;
	alasql.databases[databaseid] = self;
	self.tables = {};
	self.views = {};

	// Objects storage
	self.objects = {};
	self.counter = 0;

	self.indices = {};
//	self.fn = {};
	self.resetSqlCache();
	self.dbversion = 0;
	return self;
};


/**
    Reset SQL statements cache
 */

Database.prototype.resetSqlCache = function () {
	this.sqlCache = {}; // Cache for compiled SQL statements
	this.sqlCacheSize = 0;	
}


// // Main SQL function

/**
    Run SQL statement on database
    @param {string} sql SQL statement
    @param [object] params Parameters
    @param {function} cb callback
 */

Database.prototype.exec = function(sql, params, cb) {
	return alasql.dexec(this.databaseid, sql, params, cb);
};

// 	// Compile
// 	var statement = this.compile(sql);
// 	// Run
// 	if(statement) {
// 		var data = statement(params, cb);
// 		return data;
// 	}
// 	return;
// };

// // Async version of exec


// Database.prototype.aexec = function(sql, params) {
// 	var self = this;
// 	return new Promise(function(resolve, reject){
// 		alasql.dexec(this.databaseid,sql,params,resolve);
// 	});
// };


// Aliases like MS SQL
/*
Database.prototype.query = Database.prototype.exec;
Database.prototype.run = Database.prototype.exec;
Database.prototype.queryArray = function(sql, params, cb) {
	return flatArray(this.exec(sql, params, cb));
}

Database.prototype.queryArrayOfArrays = function(sql, params, cb) {
	return arrayOfArrays(this.exec(sql, params, cb));
}

Database.prototype.querySingle = function(sql, params, cb) {
	return this.exec(sql, params, cb)[0];
}
Database.prototype.queryValue = function(sql, params, cb) {
	var res = this.querySingle(sql, params, cb);
	return res[Object.keys(res)[0]];
}

Database.prototype.value  = Database.prototype.queryValue;
Database.prototype.row    = Database.prototype.querySingle;
Database.prototype.array  = Database.prototype.queryArray;
Database.prototype.matrix = Database.prototype.queryArrayOfArrays;


// Compile statements
Database.prototype.compile = function(sql, kind) {
	return alasql.compile(sql, kind, databaseid);
};

*/
// 	var self = this;
// 	var hh = hash(sql);

// 	// Check cache with hash of SQL statement
// 	var statement = this.sqlcache[hh];
// 	if(!statement) {

// 		// If not fount, then compile it
// 		var ast = alasql.parse(sql);
// 		// Save to cache

// 		statement = this.sqlcache[hh]= ast.compile(self);

// 		// Memory leak prevention 
// 		this.sqlcachesize++;
// 		if(this.sqlcachesize > alasql.MAXSQLCACHESIZE) {
// 			this.resetSqlCache();
// 		}
// 	};
// 	return statement;
// }

// SQL.js compatibility method
//Database.prototype.prepare = Database.prototype.compile;


// Added for compatibility with WebSQL