Updating sql tables when joined
Pinal is also a Cross Fit Level 1 Trainer (CF-L1) and Cross Fit Level 2 Trainer (CF-L2). For any SQL Server Performance Tuning Issue send email at [email protected] Col1 IN (21, 31) GOPinal Dave is a SQL Server Performance Tuning Expert and an independent consultant. If you omit the WHERE clause, all records in the table will be updated!When asked the reason was he had no idea how to use multiple tables with the help of the JOIN clause in the UPDATE statement. Additionally, we want to update the values of Col2 and Col3 only. When you look at this it looks very simple but when we try to think the solution, I have seen developers coming up with many different solutions for example sometime they write cursor, table variables, local variables etc. Col2)) UPDATE CTE SET Col1 = _Col1, Col2 = _Col2from stackoverflow.“UPDATE Table1 SET Col2 = t2. You can expand or narrow the results of your search by specifying the type of join you want between tables.
As you can see that using JOIN clause in UPDATE statement it makes it very easy to update data in one table from another table. Col2 AS _Col2 FROM T1 JOIN T2 ON T1= T2/*Where clause added to exclude rows that are the same in both tables Handles NULL values correctly*/ WHERE EXISTS(SELECT T1.
The following code example creates a query that retrieves only those company names from the Customer table that have orders in the Orders table, the order numbers for only those companies, and those names belonging to employees who took those orders.
The example uses two inner join clauses to display only those records from the three tables that match on the Cust_ID and Emp_ID fields.
CLOSE ALL CLOSE DATABASES OPEN DATABASE (HOME(2) 'Data\Test Data') SELECT TAlias1.company, TAlias2.order_ID ; FROM customer AS TAlias1 ; INNER JOIN orders AS TAlias2 ; ON TAlias1.cust_id = TAlias2.cust_id ; ORDER BY TAlias1.company ASC You can specify more than one join operation to include data from other tables.
For example, suppose you want to create a query containing only those companies that have orders, only those order numbers for those companies, and the employees who took the orders.