#41 Add support for sum()

src/dml/query-builder.ts

@@ -696,6 +696,10 @@ export class DatabaseQueryBuilder extends StatementBuilder {
 			this.max(fn);
 			break;
 
+		case DatabaseFunctionKeys.SUM:
+			this.sum(fn);
+			break;
+
 		case DatabaseFunctionKeys.CURRENT_TIMESTAMP:
 			this.currentTimestamp(fn);
 			break;
@@ -732,6 +736,21 @@ export class DatabaseQueryBuilder extends StatementBuilder {
 		return this;
 	}
 
+	public sum(fn: DatabaseFunction): this {
+		this.sql.append('SUM');
+		this.sql.openParens();
+
+		if (fn.params.options.distinct) {
+			this.distinctStatement();
+		}
+
+		this.expression(fn.params.expr);
+
+		this.sql.closeParens();
+
+		return this;
+	}
+
 	public currentTimestamp(fn: DatabaseFunction): this {
 		this.sql.append('CURRENT_TIMESTAMP');
 

src/functions/function-token.ts

@@ -12,6 +12,7 @@ export enum DatabaseFunctionKeys {
 	COUNT,
 	MIN,
 	MAX,
+	SUM,
 	CURRENT_TIMESTAMP,
 }
 

src/functions/functions.ts

@@ -34,6 +34,23 @@ export class DatabaseFunctions {
 		};
 	}
 
+	public static sum(
+		expr: Expression,
+		options: {
+			distinct?: boolean;
+		} = {}
+	): DatabaseFunctionToken {
+		return {
+			riao_expr: ExpressionTokenKey.FUNCTION_CALL,
+			fn: DatabaseFunctionKeys.SUM,
+			type: ColumnType.BIGINT,
+			params: {
+				expr,
+				options,
+			},
+		};
+	}
+
 	// ------------------------------------------------------------------------
 	// Date/Time functions
 	// ------------------------------------------------------------------------

test/spec/functions/sum.spec.ts

@@ -0,0 +1,38 @@
+import 'jasmine';
+import { DatabaseFunctions } from '../../../src/functions';
+import { DatabaseQueryBuilder } from '../../../src/dml';
+import { columnName } from '../../../src/tokens';
+
+describe('Function - sum()', () => {
+	it('can select from number literal', async () => {
+		const { sql, params } = new DatabaseQueryBuilder()
+			.select({
+				columns: [
+					{
+						query: DatabaseFunctions.sum(1),
+						as: 'sum',
+					},
+				],
+			})
+			.toDatabaseQuery();
+
+		expect(sql).toEqual('SELECT SUM(?)  AS "sum"');
+		expect(params).toEqual([1]);
+	});
+
+	it('can select from column name', async () => {
+		const { sql } = new DatabaseQueryBuilder()
+			.select({
+				table: 'user',
+				columns: [
+					{
+						query: DatabaseFunctions.sum(columnName('id')),
+						as: 'sum',
+					},
+				],
+			})
+			.toDatabaseQuery();
+
+		expect(sql).toEqual('SELECT SUM("id")  AS "sum" FROM "user"');
+	});
+});