![]() To add a computed column definition to an existing column On the File menu, select Save table name. Indicate whether the data is persisted by choosing Yes or No from the drop-down for the Is Persisted child property. For more information, see CAST and CONVERT (Transact-SQL). For example, if a column of type nvarchar is combined with a column of type int, the integer type must be converted to nvarchar as shown in this formula ('Prod'+CONVERT(nvarchar(23),ProductID)). Use the CAST or CONVERT function to resolve the data type conflict. If the conversion is not a supported implicit conversion, the error Error validating the formula for column column_name. When a formula combines two expressions of different data types, the rules for data type precedence specify that the data type with the lower precedence is converted to the data type with the higher precedence. For example, in a SalesTotal column, the formula you enter might be SubTotal+TaxAmt+Freight, which adds the value in these columns for each row in the table. In the (Formula) child property, enter the expression for this column in the grid cell to the right. In the Column Properties tab, expand the Computed Column Specification property. For more information, see Data Type Precedence (Transact-SQL). For example, if the formula references a column of type money and a column of type int, the computed column will be of type money because that data type has the higher precedence. The Database Engine determines the data type of the computed column by applying the rules of data type precedence to the expressions specified in the formula. ![]() Right-click Columns and select New Column.Įnter the column name and accept the default data type ( nchar(10)). In Object Explorer, expand the table for which you want to add the new computed column. Use SQL Server Management Studio To add a new computed column For more information, see SET QUOTED_IDENTIFIER (Transact-SQL). SET QUOTED_IDENTIFIER must be ON when you're creating or changing indexes on computed columns or indexed views.A computed column can't be the target of an INSERT or UPDATE statement.For example, if the table has integer columns a and b, the computed column a + b may be indexed, but computed column a + DATEPART(dd, GETDATE()) can't be indexed, because the value might change in subsequent invocations. However, if the computed column value is defined by a deterministic expression and the data type of the result is allowed in index columns, a computed column can be used as a key column in an index or as part of any PRIMARY KEY or UNIQUE constraint. A computed column can't be used as a DEFAULT or FOREIGN KEY constraint definition or with a NOT NULL constraint definition.You can specify an expression for a computed column in SQL Server by using SQL Server Management Studio (SSMS) or Transact-SQL (T-SQL). A computed column expression can use data from other columns to calculate a value for the column to which it belongs. In our example above, we multiplied the price of each product by its quantity from one table ( purchase) and then multiplied this total price by the percent discount using the discount table.Applies to: SQL Server Azure SQL Database Azure SQL Managed InstanceĪ computed column is a virtual column that isn't physically stored in the table, unless the column is marked PERSISTED. P.price * p.quantity * (100 - d.value)/100 AS total_priceĪs you can see, it’s quite easy to multiply values from different joined tables. We have another table in our database named discount that has columns named id and value the latter represents the percent discount on the item with the given ID. Note that you can also use data from two columns coming from different tables. You can give this result an alias with the AS keyword in our example, we gave the multiplication column an alias of total_price. ![]() This query returns records with the name of the product and its total price: nameĭo you need to select the name of each record (in our case, name) and compute for it the result of multiplying one numeric column by another ( price and quantity)? All you need to do is use the multiplication operator ( *) between the two multiplicand columns ( price * quantity) in a simple SELECT query. Let’s multiply the price by the quantity of the products to find out how much you paid for each item in your order. Our database has a table named purchase with data in the following columns: id, name, price, quantity, and discount_id. You want to multiply values from two columns of a table.
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